 I even assume now that you've heard me enough that even at night when you're sleeping that my voice is ringing in your ears. Alright, so let's keep our conversations up and about. Remember in the last lecture there's always, you know, this thing by the end of the lecture you feel that some things you could have talked about, you should have talked about and you wish you had more time. So in some sense, the last lecture I had shared some of the examples of things that we do in the class. Since there's an opportunity here, I just really want you to know that there's one aspect which is the content, okay, which is important. But for me, the transformation that can happen for a student in their relationship with their own selves, their work, their relationship with environment, their sense of responsibility. I just see every contact moment, every opportunity that I have in contact with them as an opportunity to be able to forward that transformation. So again, it's very personal, you know, and so whatever I'm going to share with you is things that I have experimented with and never been disappointed, I've always been very delighted by the kind of responses that one has got. So I'm just going to share them with you and if you're already doing some of these things great, if you'd like to add it to your palette, so to say for painting your own lectures, you're welcome to do that. If there are ideas that you have, please make sure that you send them, okay, on the Moodle and we'll have it be available for everybody. I'll open up a new conversation in Moodle, which will basically allow all the fellow teachers in this group over here to be able to say what exciting things do they do in their classes and what is it that they found successful, where is it that the students are delighted, where is it that they've actually seen that with very minimal effort, they can make a biggest difference for their students. So let's open up the, I think it's an important part of the overall forum that we are in. Okay, so what I'm going to share with you is some of the examples of questions or I'm saying an example. So this is questions for air quality module. This is just one example of many questions, okay. I'm sure there would be things that you can then add to it. All right, so let's begin. So I'm just going to go over these questions are based on the materials that are covered during lectures and home assignments. It's pretty much things that we have done in our class, in our lectures over here. We haven't actually been able to show some films or we haven't actually used some of the time for any field studies, etc. But whatever we could do in the classroom in this particular mode, remote center mode, we have actually brought to play. And so the premise is that the questions that we're going to be asking are only questions that we have actually been able to deal with in the class. And home assignments. I think a lot of times real learning happens when students go back, do some reading, do some group work, learn from each other. And then when they submit the assignment, in fact, in the writing of the assignment, sometimes they find out that maybe they're not very clear about, they thought it was clear, but when they start writing, they find out oops, it's not going to happen or it's not clear. So invariably I tell students that they should not start working on the assignment one day before that they should actually finish it at least three, four days before, at least start it to finish it three, four days before so that when they're doing it, they realize they don't understand parts of it and they still have time to be able to go back. I'm not a stickler for people submitting by a certain time, although it makes it logistically very difficult to deal with it if people don't submit or if everybody doesn't submit by a certain deadline. People even ask whether they'll be penalized for submitting late. And different people have different opinions about it. For me, what's important is that if somebody is committedly doing the work, I should not be engaging in the question of penalizing. And if that penalty had really a benefit, I would probably think about it, but I'm not too sure whether it really would have a benefit in this particular case. So there are places where I do use a deadline, but this is one place where a lot of times when they're engaged in things which are not necessarily in their mainstream and something which is at the level of you impacting at the level of transformation of the human being himself or herself, I want to give the time that is required for it. So this is basically the material covered, I'll just list it. So we talked about dispersion, atmospheric stability. We talked about characterizations or characteristics of particulate matter. Respirable matter, PM10, PM2.5. Trimodal distributions. Chemical nature as a function of size. Smaller particles are more toxic. Larger particles may be benign. How to characterize nano-sized particles, the different instruments that are used. How you would control gaseous pollutants and how you would control particulate pollutants. Then here are some movies. These two movies I'd given them to you, talked to you about them already. Smog Incorporated is a film which was made maybe now about 15, 16, 18 years ago, I forget the exact date. By Center for Science and Environment, this is a CSE, this is based in Delhi. It used to be, it was founded by Dr. Anil Agarwal. He passed away now, but in the film he talks to his audience about issues we're dealing with with regard to air quality. And some of the issues they had raised, looking 20 years ago, actually have led to implementation of public transport systems, etc. J. Ramakrishna, this video link I will give to you. I don't know, there won't be a chance to show it. We'll see, if I can, I'll show it to you, but it's a long video too. So you should see it at leisure, and I show it to the students. I show about first 40 minutes in the class, and then I give them an assignment, which is based on the remaining 100 minutes of the video. So then that way they get to see the video. And these are at the national level, issues that are being dealt with, issues that have been dealt with at the policy level, issues that have been dealt with at the structural level, some of those issues. I think you will enjoy it. I don't know about students, they'll probably get some value out of it for sure, but you would definitely enjoy seeing this video. One night in Bhopal, this is a BBC documentary about the Bhopal gas tragedy. I show this movie especially to bring about a contrast between routine industrial operations and some accidents or disasters. The accidents and disasters typically don't fall in the purview of environmental science and engineering. They have, anytime there's a disaster, anytime there's an accident, there is a different team, different administration, section of the administration that would deal with it. But this was related with the air quality. And some of the things that, some of the concerns that are within an organization, some of the concerns that might be there while planning. So one of the things, for example, it's pointed out, not in the movie, but otherwise, is that when this particular plant was set up, for several, for a large distance around the plant, there was nobody living. It was not habitated, it's not populated. But over a period of time, because there was industrial activity, economic activity, people started moving in closer. So a large number of people got affected also because it was pretty close to the point of release. Okay, so those are some of the movies. They're always fun, students always enjoy it. And also one thing about One Night in Bhopal, I usually caution the students a little bit. It's a pretty, it can be a very disturbing movie. Why I'm saying that is because when I'm sitting with the students and watching this film, by the time the film gets completed, I have at least cried a few times throughout the movie. And it doesn't matter when I see it, how many times I've seen that movie. But any time I see it, it still moves me to tears. And so you just gotta be responsible that somebody is sensitive about it, that they know should or should not watch the film, depending on that. And by the time this movie is done, at the end of the lecture, there's not much left to say, okay? And you just, so it's a very, the ending is very sober, very somber. So people tend to leave with that kind of a sentiment after the film. And in the homework set then we have given, we've done global warming one homework, we do one informal homework in which you ask students to read this review paper by Molina and Molina, which I have sent to you. I have not in the past sent them Pope and Doc repaper, which I've sent to you. But I think in the next semester, I'll probably have the students read that paper also. And then one assignment invariably is on, if you were in charge of the air quality management in your city, what would you do? And this is an assignment, so they can work on it on their own. All right, and then the key thing that I operate around is 20 questions and 20 answers, okay? Let me tell you a little bit about that. Before we do that, the material that I gave, I always tell them that this material is to be used as pointers to prepare for the exam or for the, just giving the slides is not adequate. You gotta read the reading material, you gotta go watch short films, etc, etc. So all that needs to be done, you need to go to the library. A lot of times I tell students, hey, you cannot avoid going to the library just because you got some PPT slides on Moodle and just because you got some films, that is not the entire picture. You gotta go for yourself and figure out what are the concerns, what are the issues, and visit the library. So use books to go and understand. And then if you have any questions, I usually ask them to send an email. But also, I usually keep one hour, one hour during the week. Where if anybody has any questions, that they can come and ask me. Because in a class of 300, it's usually difficult to be able to address one on one. But if you give them an opportunity, then at a particular hour. Wednesday afternoons usually we don't have any classes. It's a time which is reserved for institute meetings, departmental meetings, institute seminars, etc. So Wednesdays there are no classes. So usually those seminars, etc, begin after 3 o'clock. So Wednesday 2 to 3, I usually seize a good time for most students to be able to come if they have any questions. So then now the 2020, right, the 20 questions, 20 answers. This is an idea that I have stolen from Professor Tom Hauser. He used to work at the United States Environmental Protection Agency, senior person. He retired and after retiring, he joined the University of Cincinnati in our department. He was teaching this course on air resource management, okay. He didn't like the word pollution. He didn't like the word quality. So he actually offered a course in air resource management and he said, we really need to begin to relate with air as a resource. So he took this course and he would, winter mornings, 8 o'clock in the morning, he would start his lectures and all of us would be there because he's a very good teacher and also very experienced. So it was important that we not miss any of his classes. So middle of the snow in Cincinnati, he used to kind of land up in classes and half the time, we would be a little shivering, but it used to be a good class. I recall those classes quite fondly. And so what he would do in the class was, he said, I'm going to give you 100 questions. And I'll only ask from these 100 questions in the final exam. So his whole outlook was that if by the end of a three month course, you are able to answer these 100 questions, then the course got handled, that you got whatever I wanted you to get, okay. I really like the idea. And in some sense, there's also no surprises. This is closed book, closed notes. So you actually had to remember some of the standards and some of the other things that required memory. So he actually wanted us to memorize those. But he would only ask from these 100 questions. So the definition was well in place. So then we knew what to kind of be doing. I do the same thing, but instead of, because it's a short, I just have six or seven lectures. So instead of doing 100 questions, I do 20 questions and 20 answers, okay. However, I also tell the students that I will ask some creative questions, okay. So to synthesize some of the things that they have learned in these 20 questions, you'll have to put them together in a way in which it then becomes applicable, okay. So that's, I just wanted to acknowledge Professor Hauser's teaching the course that I learned from him. So here we start with our 20 questions. And you should know that I give these 20 questions and I also give their answers, 20 questions, 20 answers. But it's a closed notes, it's a regular exam. So they have to, if they need to remember, then they need to remember some constants or some of the other things if they need, I give them as a part of the question itself. But otherwise, they can't suddenly want to open up their notes to see what are criteria pollutants. That now, by the end of this six lectures, seven lectures, they need to have memorized what are the criteria pollutants, okay. Or what is the standard for particulate matter? Or what is PM10? These are things that they need to remember. There are some which are memory level, some for example, YPM 2.5, YPM 10. There's a logic to that, that logic also gets tested out. So the first question, for example, is what are the classes of air pollutants and how are they managed? Now this is something which we've gone through in these lectures here itself, but I'm just going to formally now give it to you as an answer so that, you know, actually I'll just be quiet for a second. Why don't you just read through that slide? Okay, I'll be quiet for a second. You read through that slide. I'll give you a minute. So see I give this to the students at least two weeks before the final exam. So then in the classes that follow, lectures that follow, or on the Wednesday that I have the office hours for them, they can come and ask questions. Okay, so that really helps. You let them know well ahead of time, this is the question, these are the answers. And again, these are all bullet points, okay. They're not really descriptive answers, but these bullet points, if they went to Google and they search for it, they'll be able to find answers. So in some sense, what I had said in the earlier slide that use these as pointers, not necessarily the entire material. And no matter how much, you know, we do, I'll not be able to spend like a couple of hours on this criteria pollutants, for example, in this set of lectures. So therefore it's important that you tell them, look, this is the question, this is the kind of answer that is expected or these are the pointers to the answer and then they can do their own reading or their own studying. So for example, they might want to know what trading permits are. They might want to know, oh, what is this MOEF, CPCB, CPCB? This is in some way the structure of how we manage environment quality in the country. Industry, there are emission factors for sources. So for example, if you have a coal power plant, then depending on the size of the plant, if suppose it's a 1000 megawatt plant and for every megawatt you're allowed to emit a certain amount of sulfur dioxide, then what can be expected from a 1000 megawatt plant? So there are some emission factors that are available and or for cars, for example, carbon monoxide milligrams per kilometer traveled. Those are things that you can know the number of cars or you know the number of kilometers traveled and you're multiplied by that factor to get a sense. So these are things which we have covered in the class. These are pointers. This would be the answer to this question. Next, we've again dealt with this quite elaborately. How is the effect of a source estimated in the ambient? So I'll be quiet for a minute now, so please look through the slide. Okay, so the question for example that I might ask is what are the input data required to run a Gaussian flow model? Inputs would be meteorological conditions which is temperature profiles of the stability, wind conditions, source strength and the stack height. These are the three main inputs that would go into running a Gaussian flow model. What is a windrows? Now by now everybody knows what a windrows is, but there are three things that I would ask, what are the three key information components of a windrows? And the answer is wind direction, wind speed and the frequency. And sometimes if they give those three, I give them full marks. If they draw it sometimes, but they haven't said these very clearly, but they've indicated it. As long as I have a sense that they understand what a windrows is, I would give them full marks. Lapse rates, we've gone through this. Environmental lapse rate is the actual vertical temperature profile as measured for example by using a weather balloon. So this is the stability is based on these. Now, let's take a look at this. Then I usually would ask, not this is the same as what we did in the class here, that create a different scenario in which to say, would this be a condition of stability or would this be a condition of unstable? So for example, we did that class exercise in which I had asked you to give me a response, correct response C or D. So then the correct answer was D. So I would give something like that. So they can actually test out for themselves whether they understand what this whole business of stability vis-a-vis the lapse rates means. Okay, then since we've talked about particles of different sizes, small sizes, large sizes, medium-sized particles, et cetera, it's important to understand if you had suspended particles in the atmosphere, what would happen to them? There were no chemical transformations happening. What would happen to them physically? What would happen to their dispersion? How will they get removed? So the question then is, what are the removal mechanisms for larger smaller particles in the atmosphere and somewhere greater than one micrometer as the size increases, particle gets heavier and heavier and therefore it's greater chance that it'll get settled out. Whereas if the particles get smaller and smaller, they would removed by virtue of diffusion. So somewhere in between here, it's neither small enough nor large enough to be able to get removed. So therefore it tends to accumulate in the atmosphere. So this is right around the place where that accumulation mode occurs. You understand this now by now? What are the three plots in this graph? So this is actually, I should probably change it. This is, there are only two plots over here. One is based on number distribution, the other one based on mass. Now in my earlier slides, I've given you another graph where we talk about the places in the lung in the respiratory system where deposition will take place. So that was supposed to be the third of the plot. Earlier I had on the same graph but now I've separated it out. So there are three plots. One is the number size distribution. The other one is the mass size distribution and the third plot to see where deposition will take place in the lungs. The larger particles will tend to deposit up here whereas the smaller particles they tend to go all the way to the alveoli and there's a good 70 to 80% chance that they will deposit over there if it is in the range of about 0.1 micrometer or so. So not everything that you inhale will get deposited. Everything that you inhale, parts of it will get deposited and when you exhale, most of it will come out but there is a particular fraction that has the highest chance of depositing in your lungs. So those are the plots. What are the likely sources of these three modes? So the answer to this question is in the next slide. This one, AB are already here. C, I have not, C is a separate slide which is not here right now but the three modes, what are the different sources? So nucleation results from nucleation of vapor to droplet and get together to form an elephant. That's nucleation or chemical reaction, for example, in combustion, you have suit formation. Accumulation results from coagulation of smaller particles and secondary aerosols which get formed in the atmosphere. Coarse mode, it's source, the source of coarse mode particles are dust and treatment, sandstorms, et cetera. Question number nine, what are the possible pathways for the formation of particles in different modes? So here you talk about combustion and you're talking about bottom ash, larger particles. You talk about smaller particles which come because they get nucleated or they get entrained in this combustion system. The next question was how would you size these aerosol particles which is one of the lectures we had done in this training course? So you go through optical microscope. I really want them to know what are the different instruments that are available. And somewhere when we are talking about that synthesis, I actually asked them to make a choice of an instrument that they would use which would be appropriate for that application. So we'll come to that in a little bit. How does the electrical mobility principle, how is it used? Basically, you take charged particles, you put them in an annular space which has an electrical field it'll follow a certain trajectory. One particular trajectory will follow a particular window. That's the sizing. So you size it based on the electrical charge and the electrical field and then you change the electrical field and you'll be able to capture a different size. So this is explained, all explained over here. This is after you have sized them, how do you do the counting? You basically introduce the particles. Again, these two slides have given in the previous lectures, they look slightly different but it's exactly the same thing. So particles enter here, this is an alcohol saturated area. So as particles are going through, they get bigger in size by virtue of condensation of the alcohol vapor and as they go further down, they get detected here optically. Optically you can detect up to about 0.1 micrometer. That's about 100 nanometers. So particles of 3 nanometers would have to be grown to that size. They would have to be fattened up so that they can be detected by optical method. Cascade impactor, again, it's important for students to be able to differentiate that the key principle of this instrument is the ants and the elephant concept. You have these baby elephants, you have these medium elephants and you have these big elephants. And of course, what you don't see at all over here because they're so small are all the ants, the gas, which is carrying these. So by virtue of the size of the nozzle, progressively as you keep going down the cascade, you keep decreasing the size of the nozzle. When you decrease the size of the nozzle, the velocity increases. So a particle which did not have enough inertia at the first stage, by the second or the third or the fourth or the fifth or the sixth or the seventh or the eighth or the ninth or the tenth stage, they basically, increasingly, progressively, we are increasing the velocity and therefore smaller particles will find it difficult to be able to take that 90 degree turn and therefore will impact out. So this is important for them to understand. This is routinely used in the field. Scanning mobility particle size is lab equipment. Although they have a field version also, there's an instrument company called Grimm, a German company that makes these portable scanning mobility particle sizes also. But in the lab, the larger systems are kept in the lab. These are portable. So suppose you wanted to go and do some testing in a kitchen, you probably will not take the entire scanning mobility particle size. You'd probably take some instrument like this. So you take a small optical particle counter or you take some other. So the choice of that instrument therefore becomes, one aspect is the principle. The other part of it is, which one would you choose for which application? Okay, I spend a little bit of time on this because this is stuff that very basic. Anybody who's any course on air pollution, basics of air pollution should understand this. So we say, what is PM10, what is PM2.5? So this by definition is clear. One of the things I've not written over here, but PM10 is a concentration of particle. So there's one aspect which is the size. So anything smaller than 10 micrometers in this particular case, anything smaller than 2.5, anything meaning the mass, the mass concentration and the mass concentration is given in micrograms per meter cube. So anthropogenic sources, combustion, industry vehicles, they emit particles predominantly in the about or less than 2.5 micrometer size range. So PM2.5 is the mass of particles or mass concentration of particles smaller than 2.5 micrometers and is a measure of anthropogenic sources. It's a measure of man-made sources. It's our human activity that is giving rise to this 2.5. So this has a greater health concern as these particles may be more toxic. So PM10, PM2.5, PM2.5 is always a subset of PM10. PM2.5 is already included in PM10. If you just take PM10, you'll only be able to see the total mass less than 10 micrometer. But if you also specify PM2.5, then it is saying, okay, overall in PM10 is so much mass, but if I were to just take fraction less than 2.5, then PM2.5 is that fraction of the PM10. Second part of this question is contextual again, what could be the difference in the size distribution of amide at a road crossing in peak traffic hour and a rural site in Tha desert, for example. The Tha desert would have a lot of crustal matter, sand particles, et cetera. So it's in the course mode, whereas at a busy road crossing, if there's a lot of traffic, then you'd basically get combustion emissions from IC engines, and that would be in the PM2.5, okay. So the relative mass fraction of PM2.5 for the traffic crossing site is more. So there are more particles in the 2.5 range in a traffic signal. It may not have enough particles in the course mode, because they may not be dust in that traffic. But if you go to a village in Tha desert, then the traffic may not be there, combustion may not be there, but definitely they'll be in the air, there will be particles because the sand is still suspended in the gas phase. Then this is just a summary of the control systems, okay, control methods for air quality in air pollution. So there are two parts. One part is the particulate matter, and the other part is the gaseous, okay. Gaseous pollutants, particulate pollutants. And what I usually say, I give the names over here, and then I give the principle, okay. What is the principle on which that particular control device works? So settling chambers are usually gravity-based. Cyclones, because particles are now small, gravity may not work. So you actually provide the inertia by introducing it tangentially and using the pumping basically to increase the inertia. Scrubbers, you basically physical contact with liquids. Rain is a good scrubber, okay. Electrostatic precipitators where you use electrical mobility. You charge a particle and you put it in an electric field between two plates, and the particle will migrate because of electrical mobility. Filters we discussed, I think I even demonstrated my lovely handkerchief to you and showed you that particles are removed by the tortuous parts that are in the fabric, okay. So there is interception, there is impaction, and there's diffusion. All three mechanisms are in play in fabric filtration. The second part is gases, how to control gaseous pollutants. Again, if the gas molecules, if the ants, if those particular specific ants, the sulfur dioxide ants and the oxides and nitrogen ants and the ammonia ants, if those have affinity for water, then you can bring them in contact with water. You create artificial rains, so to say, not the artificial rain by seeding the clouds, but you create a chamber in which you have these little nozzles in which water is being sprayed and gas, the dirty gas or the polluted gas is brought up in contact, and as the gas is coming up, the molecules of the gas or gas molecules which are soluble in water will get taken away by solubility, and then the cleaned up gas would go out of the chamber. Absorption is slightly different. It is at the affinity at a solid surface, granular activated carbon is one example. There are many, many new adsorbents that have been created which are used for very specific purposes. So they are also adsorption. A lot of times it's also coupled with catalysts and you can have catalytic reactions that take place in the packed bed or in the, what should I call it? The porous structure that they create in which the reactions can take place as well as adsorption can take place. Incineration is a very viable, very used, very powerful way of, very quickly removing some of the hydrocarbon pollutants which are too low in concentration to be recovered economically, but at the same time, you don't want to dispose it off in the atmosphere as a hydrocarbon, so you burn it, and you burn it well, okay? You burn it such that it converts completely to carbon dioxide and water. If you don't burn it well, you get the black smoke, which is not a good idea. And of course in some special circumstances, they also use membrane separation. What is the structure of Earth's atmosphere? I don't do much with this really, okay? Other than at some point in time when I'm talking about stability and the lapse rate, I use the first 10 kilometers or so to establish what is an average lapse rate. It turned out to be 6.5 degrees Celsius for every kilometer. So the rest of the structure is available. Stratosphere people, everybody knows it's the ozone layer. So just above the troposphere, there is a stratosphere. And if they're talking about good ozone, then that's where the good ozone is. That's where we have a concern about the ozone hole. But if you really ask about 80% of the masses within this troposphere, the first 10, 12 kilometers, and that thickness varies depending on which part of the planet you are on, okay? So I expect, I tell them, listen, you should know this. I usually don't test them. I mean, it's something that they'd have to commit to memory. It's a good idea. I mean, it's just four names to remember. Troposphere, stratosphere, so mesosphere and thermosphere, okay? And they, of course, can go to Google and check some more on this. What is the difference in the incoming and outgoing radiation on Earth? Global warming, that's what we're talking about. How do the presence of different gases vapor influence the radiation balance? Okay, this is something which everybody understands by now. But then I've shown this, I've given this in the previous slides also. It's good to have, I actually ask students to give the solar and the terrestrial spectrum. So they actually draw this. They don't have to draw this. This is too elaborate. But at least this part, they can draw on the x-axis is a wavelength and on the y-axis is the spectral intensity. And so they actually can say, okay, this is a visible part. Here's the infrared. Most of the emissions that are coming from radiation that is coming from Earth as a black body are in the infrared. And infrared is where most of the absorption is taking place. So carbon dioxide absorbs here, water vapor absorbs here, methane and other, they absorb in this band. This band over here, they're all transparent. When the radiation is coming in, methane molecule transparent, CO2 molecule transparent, water molecule transparent. But when it goes down there, it heats up the Earth. Earth is at a certain temperature. It re-radiates. When it radiates at a higher wavelength, at that wavelength now it becomes opaque. So that's basically something that they can very nicely understand from this and be able to also give a responsible answer. What are the possible implications of global warming? Again, from the movies now, I think from the two movies, one thing becomes very clear. While some people may be convinced that it is caused by human activity, some people may be convinced that it is caused by flares on the sun, that global warming is happening is quite evident. Different models will tell you different time frames in which the impact is gonna happen. Some people are saying that we've already started seeing the impact of it. Some people are saying we may reach the point of no return very soon. These are all now uncertainties and different people argue differently, et cetera, et cetera. But one thing is for real is that there is global warming and there will be impact. And a lot of places they have very specialized groups that are exclusively working on abatement of global warming, how to respond to impacts that the global warming would have, et cetera. This is just some point, just to sensitize, just to know whether students understand what are the kind of implications that would... What would be the implications for a country like India, for example? I know everybody keeps talking about a particular part of the world or some parts of the world which are below sea level, which would get submerged, that entity would completely disappear if the sea levels were rising. But then what about parts of India where you've had rains and all the populations are established there because they've had water for centuries and centuries together. If you look at civilization, it is actually oriented around where water was available. And if suddenly over the next 50 years, over the next 100 years, the place where that water becomes available shifts, what happens to these new cities? Are we planning in a way to look to see what might be a way of dealing with these water resources? Agriculture is going to get impacted. The amount of energy available, there are many studies where they're looking at productivity versus availability of moisture, availability of sunshine. Clouds will begin to cover. In the north, for example, the fog, the Indo-Gagetic fog, sunlight's not available. If sunlight's not available, how are plants going to grow? Okay, so those are some of the concerns that are there. So, you know, students can begin to get a picture of this by reading some more. So not all greenhouse gases are similar. Again, we've discussed this. They have global warming potential, different global warming potential, GWP. This also tells you the lifetime of a particular molecule in the atmosphere. The longer something is in the atmosphere, the chances are that it'll have more potential. But again, it depends on the model. It depends on what reactions might take place, et cetera, et cetera. So all of this is a study by itself. If somebody's excited about it, wants to do more work on global warming, on greenhouse effect, et cetera, et cetera, for as a part of their master's work or PhD work after they graduate, hey, this is, you know, some of these are pretty well established, but some of them are still open for research and there is funding available. Albedo, I actually have them do a little simple exercise in which they basically are saying, what is the total amount of solar radiation that is being received? And alpha is the amount that gets reflected back. That's Albedo. So right now it's estimated at 0.31. I usually tease them a little bit and say, how did you know it was 0.31? Well, what if it was 0.32 or what if it was 0.30? And actually then give that to them as a question. So if the Albedo changed from 0.31 to 0.30, what would be the new temperature for the planet? Okay, just a small, you know, one in 30 is about 3%, 3% error. In estimation of Albedo can completely change the entire calculation. So it's pretty that sensitive and that uncertainty around that is much higher. So those are some of the sensitivities. You want to sensitize them to where a particular small number can change the entire way we look at radiation balance or the future of the planet. So this is basically the solar energy which is striking the earth. I give them this constant in the exam, solar constant. This is the amount of energy being received from the sun by earth. And then this is the amount that's getting radiated. So here the pi r square is a projected area of a sphere and here 4 pi r square is the overall, the surface area of the sphere because the earth is radiating all the entire surface of the globe. And then when you equate these two you will get a certain number. So this is a little problem in the reading over here but 5.67 to 10 to the power of minus seven. It'll come to you. It's the Stephen Boltzmann expression over here which is given. The students remember this quite well because it is 5.678, okay? 5.67 e to the power of minus eight. That's how they remember it. I think just being able to answer those 20 odd questions is okay from a perspective of have they learned the basics, okay? But it doesn't kind of give a sense of fulfillment. It doesn't kind of give a sense of that I can actually use this information somewhere. So I usually give at least two or three questions in which this is my intent in giving those questions, okay? The intent through the exam, the entire exam, okay? Is this, that the students have developed the confidence that they have learned, okay? I mean the exam, a lot of times I don't know. My relationship with giving an exam is that if students walk out of the exam with the confidence that they've actually accomplished something out of the work that they put in, then the course really got done and this is applicable for any course. And so the level of confidence that they developed that they have learned and then the other part of it is that they can actually synthesize their knowledge for practical situations. So a lot of times the question itself is much larger than the answer. So they spend more time in going through the question, learning that, you know, understanding the question and then when the answer, if they understand from the, if the connections are made, the answers pretty straightforward or pretty simple, but that opportunity itself is used to actually forward their learning. So I'm just gonna share some of the examples of the questions, okay? So here's one of the questions and I've kind of, it's one question, okay? I told you these are long questions. I've put them in three different colors and in the exam I just give them in black print. That's not, I'm showing it over here to be able to show different aspects in the question, which will address the knowledge base needed or the accountability needed and the work then actually that needs to be done in the question. So I'll be quiet for a minute or so, I'll let you read that question. Please go ahead, okay? See the part which is in green here, I may have talked about this during the lectures, but I think it's important for them to be, before the question is asked, to actually have them get the relevance of the question, the context of the question. And if they haven't till now, sometimes students will miss lectures, if they haven't, then if I just give this last part over here, they'll never have the appreciation or the context. So this part is really to give that there is an issue, it's well recognized, who's affected by it, women and children are affected by it and so there is a problem here, we need to actually be able to assess this issue. And then you have been asked. So now as a person who has done this course, you're knowledgeable enough to be able to, you may not be an expert, but knowledgeable enough to be able to actually propose a solution. So you have been asked to estimate the pollution levels in the kitchen during a typical cooking cycle. So what is a cooking cycle, somebody might ask? Cooking cycle is when you start in the morning, when you take the cook stuff, whether it's wood based or whether it is coal based or whether it is agricultural, bioproducts, cow dung, whatever, then what would you expect? So you light it and then you bring it in the kitchen and then the cooking is done, it lasts about an hour or so. From the time that the air in the room, when you started off in the morning, assume it was clean because of ventilation, et cetera. But the moment you introduce this source of combustion in the kitchen, you now have pollutants that are getting smoke that is getting added, carbon monoxide that is getting added. And while the cooking is happening, the person who is cooking is getting affected, is getting exposed to this, might have a child who's hanging around near the mother, who's also getting affected by. So therefore it's important for us to be able to assess what kind of concentrations are we dealing with? Are they very high? Are they same as what is outside? What is the level of risk that might be there? So we can answer those questions only once we have some sense of the measure. So then the real question then is, the students has been asked to propose an experimental plan for measurements for particulate matter. So we're not going into carbon monoxide because I never covered carbon monoxide in the class. I never covered oxides of nitrogen, I never covered oxides of sulfur. Those I gave as methods, which you can do reading on your own. But particulate matter we discussed in detail. So therefore I'm saying specifically for particulate matter, what are the kind of experiments that you would propose along with the instruments that you would select and why? So this whole then thing brings in about instrumentation. Would you use a impactor? Would you use an optical particle counter? Would you use some other device? You know, how, or you would you just use a filter? Or how would you go about doing this? Okay, so that's the question. And four marks, let me just say how much? I think it's a 20 mark question for which they have about 60 minutes, which means three minutes per mark, which means about 12 minutes. It's about 12 minutes to answer this question, which is pretty good. I think 12 marks is pretty good. Okay, so that's one question. I'll give you another question. A long question, can I be quiet for about half a minute? Please read it. Okay, so I know everybody in India knows where Bubble Nagar is. I just, you know, make up some names. So Bubble Nagar is some, any city, take any city in India and we'll call it Bubble Nagar. And there is this arbitrary name that I give to a committee, the Bandhu Baye committee. Bandhu Baye means bye-bye, Bandhu Baye committee. And there is a context for it, okay? So this is the context. This part is how in reality would something like this be fulfilled? There'd be two phases. The first phase we'd collect because funding agencies would not give you a large amount of money till you've given some kind of a report for feasibility or some kind of an estimate of how much is the problem and what kind of solutions might be required, okay? So a lot of times it's done in two phases. So in the first phase, you have to collect information. Some basic information is required to characterize the geography, meteorology, extent of air pollution, et cetera. Which is what we had done actually in the last lecture where we went ahead and says, okay, let's go ahead and look at how we're dealing with Chandrapur, okay? All the steps. And these steps are also in some way mentioned here, geography, meteorology, extent of air pollution, et cetera. So please suggest the information to be collected in the first phase and the likely cost of the first phase. This is, they find it a little difficult here because at some, we never really estimate it. We never give a sense of how much is it cost to get one sample. A moody for example, to run a moody one time. If I were to do any chemistry on it and I need to collect it on a Teflon filter paper, then each run requires 10 filter papers. So which means, and each one costs about 500, 600 rupees. So one run of moody would cost about 6,000 rupees, okay? Never mind the cost of the pump, never mind the cost of the moody itself, just operationally, okay? It'll cost that much. And then of course I have to bring it in a petri slide and bring it. So it just, just want them to at least begin to engage in what could it cost? And are they going to say 50,000 for this one year study? But then they have to include their own fee as a consultant. If I'm going to be working full time on this project for a year, you'll have to give yourself some salary, right? So if you give yourself some salary per a month, you multiply it by 12, that itself is a starting point of who's going to do the work. They need to be paid, okay? So immediately it starts falling in the category of lacks now, just the salary. And then after that, you know, if you want to get meteorological data, you have to buy it. Some of the air pollution already existing data are available free online from the pollution control board, but meteorological data you might have to get. You might actually have to go location to location, looking at different sources. You might have to develop an inventory, okay? So those are some of the things that four marks, when you say four marks, and if I have a TA team that is going to do the grading, I do an interesting, I actually had, there's a need for me to do this. So I actually did this, 350 students in the class. I have 10 TA. So each TA is going to do grading for about 35 students. Now, one TA is very strict compared to another TA. So what happens is, for a similar response, this first TA gives two marks out of four, whereas the other one gives four out of four, for similar response, okay? So then there's now, you know, a problem because you are not putting everything on everybody on a similar ground. So what I started doing is, I have one of the TAs correct the same question for all the 350 students. So that way they're consistent with the grading, okay? Before they start the grading, I usually ask them, this is the question, answer it and tell me what will you give the marks for? So they'll say, okay, I'll give one mark for this, one mark for this, half a mark for this, one mark for this, half a mark for this. So they'll kind of split up the template to say, okay, if they have mentioned this, so if they've given this information, they'll get one mark. If they've given this information, they'll give half a mark. So that way, the template then gets used for the entire 350 students. I don't know how it is in your college, but at IIT Bombay, we always give a chance to the students for a CRIB session. This is for all the courses, not just this course, all the courses. And which students actually come and CRIB, they come and look at their papers and they look to see if their totals are correct. They also look to see if someplace they should have been given marks, but were not given marks. Or sometimes they will just say, sir, this is a two mark question. I got only half a mark, I deserve a little more. Something, they'll come and CRIB. So you look to see if something's going on or then you deal with it. But at the CRIB session, it becomes very easy when the TAs have themselves used a template, okay? And they're clear about what they have given marks for. So when a student comes and says, sir, I should be given one mark for this. And the TA is very clear. It says, okay, you may not, you may have been given half a mark, but for this response, I've given everybody who did it like this, a half a mark. So there's no disparity in the way the thing. So that kind of leaves students at a point of, they're not complaining after that. They left satisfied with the response. But that part of the work needs to be done. I do not allow these students, the TAs, would have done this course with me earlier, okay? So they're familiar with the material. But when we are doing the grading, I always have them take this question and answer it for themselves, discuss the solution with me. And then, so because, you know, the kind of difficulties that a student who's doing this course for the first time would have, I do want the TAs to have compassion for that. I do want students to have an appreciation of, you know, there are things which may not have been very clear in the class, which is not their fault, okay? That I will take responsibility as not having taught them well, okay? So I can take responsibility for that. There are some questions that, you know, out of 350 people, only 50 people answered correctly. So 300 people didn't get a correct answer to the question, which means that I didn't teach it well, okay? Or I need to redesign around how I teach it so that actually more and more people can, you know, do the, pass that order, you know, can answer that question well, okay? I got another example here. This is, I'll be quiet. Why don't you read it half a minute? All right, so I haven't done the colors on this, but again, it has all the elements. So it actually is saying that in your hometown, the compliance for particulate matter has been violated. The city is not in compliance. But an interesting thing has been noticed that during monsoons, PM10 decreases drastically, but PM2.5 does not change very much, okay? So what would you propose? How would you propose to manage the air quality? So this is, I think I sent a set of slides yesterday which showed that the larger particles had disappeared due to rain, the larger particles. So the contribution to PM10 had drastically changed. PM2.5 had not changed very much. So that means that the particulate pollutants are coming from combustion sources like cookstuffs, et cetera. So in such a case, what would you do to be able to control? What would you propose to the city management? Would you go to the industry and say something? Or would you go ahead and deal with the cleaning of the roads? Or would you completely remove cooking? What are the different things? What are the different ways that you can go about it? Here's another question, okay? So this one now is actually getting a little bit into the area of occupational safety and protection. So this is something that you and I see on a daily basis. We actually see construction workers or people in a mining area or stone quarries where the hair, you know, I use the same question one point in time. There is a flour mill that used to be here on campus. I think it's closed now. So anytime I would go with wheat to get the flour to this mill, flour mill, the guy inside who worked over there, he just looked like he was completely covered in the white flour. His hair actually had a little cloth that he would use to cover his hair. But otherwise all his clothes and everything would be covered with flour. And of course it always has a nice smell over there. The freshly ground flour has a nice smell. So I would see him and he would be breathing that also. So his lungs probably would be filled with some wheat flour. So we've seen that and we've seen people, even traffic police person, you know, they're standing over there. They don't really see those large particles. They may not be particles, but sometimes they have this green mask, cloth mask on their face, sometimes they don't. They're getting exposed all the time to this traffic, high traffic, especially at signals where the vehicle stop and the vehicle is idling and a lot of the emissions are getting added in that little space over there and police persons are standing all the time, even the shopkeepers in that vicinity. They've done some studies where they've seen that the cancer rates along the road are much higher than if you go even 10, 20, 40, 50 meters away. Just by virtue of the exposure that would happen. So this exposure is happening all the time. So how do you test? They say they use a mask, but they're not too sure whether it's good. So construction minestone quarry workers are seen covered with dust by the end of the day's work. They use a dust mask on the nose, mouth area to protect themselves, but unsure whether it is really useful. Can you propose some ways to test such masks? So if you are someone who knows how to use instruments for measuring particulate matter, then hey, you can test these masks and I'll just give you, I'll just make a little drawing to show you what might be a way of doing it. So, all right, so for example, in this particular case, let's say this is a human being and so let's say there's a mask over here that they put, correct? There's some kind of a mask which has some opening over here. So the concern is whether the particles over here, the particles over here, are they actually going inside or not, okay? If this filtration material, if this material is good, then these particles will not go in, okay? What you will get is clean air. Assuming of course that the mask fits, okay? If the mask doesn't fit, then we're in trouble. So, well, how would you test it? So the way I would test it is that I would actually put one small pipe here and use a filter paper and use a rotometer and use a pump over here to be able to see what amount of mask gets collected. So I'm actually getting a sense of how polluted is the air, okay? And then what I do is I do a little trick and I put a tube which has an opening inside the mask, okay? I have a tube now which has an opening inside the mask. So now I do the same thing over here, take another filter paper and take a same similar rotometer and take the same vacuum pump. And now the mask over here and the mask over here, if this filter has done a good job, then this particular filter should not have any particulate matter, okay? That's done a good job. Now, you may say this is total mass and I may be interested in size specific removal efficiency of this particular mask, in which case you can remove this, you can remove this instead of that use a cascade impactor or use optical particle counter, okay? So you can use different instruments to be able to get size distributions but this is the way you would do it. I mean, it's pretty straightforward once you understand your instruments, you're looking at effectiveness of a particular mask then you need to deal with what is the actual polluted level versus what is the air that I'm breathing. If the air I'm breathing does not have these particles, that means that the mask was efficient or you could say, hey, it could remove 80% of the particles or it could remove 95% of the particles, but not the 5% or not the 20%. That is the level of effectiveness that you would be able to then say. This is doable in the lab. This is doable in the lab. Students should kind of get excited about maybe getting, oh, if you don't want to do a mask, if you don't want to use a human being to do this, you can do it another way. The way you would deal with that is you take this particular mask material. You take this material, okay? You take a part of it, a small piece of it and you hold it in a cartridge. And then what you do is you have polluted air coming in this way and you're hoping that cleaned air will be going out this way, cleaned out air this way because this filter actually removed. But if you know what is the pollution over here, pollution level over here and then when you see the clean, you measure both. Again, either using a separate filter paper, so you can take polluted air over here, put a filter paper, put a rotameter and put some kind of pump over here. This will be A and you can take this one over here and again do the same thing, pass it through a filter paper, pass it through a rotameter, pass it through a pump, okay? So you take A and B and you compare A and B. If B is much smaller than A, then that material that the mask is made of is good filtration material, okay? So that's how you would answer that question. Students may not necessarily have that kind of a clarity, okay? So I'm not too particular whether they get a particular thing right or not as long as they are in the right direction, as long as they are thinking, sometimes they come up with some very creative solutions, okay? So the point is that you would actually, and by the way, this synthesis question, some kind of questions like this, I then grade it myself, okay? I don't give it to the TAs, because even the TAs may not necessarily have the training to be able to see whether somebody has done a good job. Sometimes they'll look, this is there, this is there, then full marks. If this is not there, this is not there, then zero marks, okay? So sometimes you can't do that in these creative kind of questions and therefore you might have to do the grading yourself. All right, here's another question. I'll be quiet for another half a minute. Please read through. There are two questions actually. One is for marks and the other one is bonus question. All right, so this question over here, you just put them in some kind of a legal situation in which say that some arbitrary United Industries Association claim that the air quality standards for sulphur dioxide are so low that one would exceed it even one strike, some simple wooden match in a room of this size, okay? So everything is given over there. Five milligrams of sulphur is given, you know it'll lead to 10 milligrams of sulphur dioxide. You know the volume of the room. You divide this mass by this volume and see make sure that it is less than this particular, this may be microgram. So assume that this is a standard, but even if you made a mistake, that's fine. That's the assumption that needs to be made, okay? So they will base their entire calculation based on this standard and then based on that say yes, the claim is correct or no, whether the lawyers are correct or not. That's something that you're able to deal with. This is a question a lot of times give just to have them not do it for an exam, but just because it is an opportunity for them to express themselves after having gone through this entire course and they are more sensitized, they have a new viewpoint. So this is like an opportunity for them to express themselves in the specific domain of environmental protection. So the question is what could ensure the quality of air and water and the cleanliness of our cities in India, okay? So this simple question, but it's also profound at the same time. I think you must have heard this several times that you see this a lot of times, you know, there's a lovely Mercedes car which is traveling on the highway and you suddenly see the window comes down and a packet of empty packet of chips gets thrown out and the windows goes out. The kind of relationship that we have about being personally responsible for the environment which is what Professor Asuleka talked about it at length actually. So what would it take? They always say that an Indian goes to another country and certainly is not throwing wrappers on the street anywhere, okay? They actually look for a dustbin and throw it. So what is it? I mean, is it apathy? What is it we need to do? The same thing with air, just any place we burn anything. It's a convenient way of getting rid of some garbage which is collected on the streets. People just burn it, so you don't have to take it anywhere. Just burn it right there. Biomass a lot of times is collect biomass and burn it. What could ensure that there would be clean air and clean water? So this is a million dollar question. Cannot imagine giving marks for this one. By the way, during the exam, students actually ask, are you serious? No marks for this. At least some bonus marks will be given. I usually tell them no bonus marks for this. This is just a question to honor you and give you responsibility for what's to come. Okay, so the bottom line that I want to communicate to you is these, I should have put the word are. These are only some examples of making the students complete the course with a sense of accomplishment and pride. For me, the course is successful if students walk away with the confidence that they have accomplished something and with a sense of fulfillment that they actually learned something. That for me is a very important component in the teaching. Anything else to be said about it? No, I think that's it. And I think now I'm on my last slide. So always being a pleasure with you. So I'll open it up for questions now. We have about 15 minutes. The kind of questions that we can ask, the openness that one would have about... By the way, in this particular course, it's closed book, closed notes because it's a large number of students. For most of my other courses, it's always open book, open notes. People usually find it a little difficult to do open book, open notes because the kind of effort that's required is something which is not the usual effort that they are used to. Sometimes I give them limited time, but a lot of times I keep it open. I give them as a take home, open notes, open book exam. Sometimes people prefer that we not give a take home that they will bring their books and they'll sit down in the exam room and we start at two o'clock, but we don't end at any time. So sometimes people, students continue to sit all the way for dinner. And so at that point in time, they can take a break, go get themselves some different to eat or something or that get themselves something to drink. But then they come back and then they continue. So sometimes an exam can go on for about six, seven, eight hours. But it's really as long as it takes for you to be able to answer that to the level of satisfaction that you think is required, go ahead. Open books, open notes, web is available. It's just that you're sitting in one room, not talking to each other and doing the work yourself, which is typically how it would be in a real life situation. I mean, when I'm sitting in my office and I'm dealing with something, I have all my handbooks, I have the web available, I have all the resources available around me. And sometimes I think it might take one hour to get the job done, but I have to skip lunch because it's going to take longer than one, two, three, four hours. And you just get it done. And then after that, you take a break and get back to work again. So I try and have it be as close to real life as possible. And in that, you're also giving them a flavor of how it might be going. I do have a way of dealing with deadlines, though. I said a little earlier that I don't keep deadlines. In other courses in some places, I actually keep deadlines to make sure that people get the importance of a deadline. If a proposal has to be submitted to a funding agency, buy a particular date and buy a particular time, if you don't do it, they will not consider it. It's in fact unfair to consider it because people who submitted on time, they may have compromised on some quality somewhere to be able to submit it on time. So in that situation, you cannot mess around with a timeline and you have a deadline that means you have to submit by a deadline. So I'll probably give you a few deadlines for the quizzes also. That's more for administrative reasons, but we have enough time. Typically, you'll have a deadline of 11.59 p.m. Okay, so there's no confusion about when the day begins and when the night ends. 11.59 p.m., so your first quiz that we're gonna give you, which starts on Friday evening, will go on Saturday, Sunday, Monday evening, Monday till 11.59 p.m. at night. So kindly follow that deadline and be able to answer as many. So we'll give you about 40 questions which will have to be completed in one hour. So you have approximately one and a half minutes per question. And these are questions that we would have addressed in the lecture, so you don't have to do much preparation. If you've attended, then great. If you want to revise, you can go over the Moodle slides one more time to get familiarized with the material that was covered. But really, it's really to just test yourself out and have some fun to look to see how much did you really learn. So if you're ready for the quiz, you can at one point in time say, okay, now I have one hour to answer these 40 questions. It's like the rapid set of questions that come one after the other. One and a half minutes, one and a half minutes. You keep, there are multiple choice. So you'll have to choose A, B, C or D. And we've in some sense randomized it so that there is no issue about getting one time. Apparently, we got a response for a quiz in which 20 questions were answered in 10 seconds. So we knew that people were doing a little bit of cheating somewhere. So we don't want to get into that. We want to keep it inside of honor. So please do your own work and test it out. We're not going to give you marks based on how much, just for you to find out what did you get, 60%, did you get 80% or you only got 30%. So if you got 80%, you still have 20% that you missed. If you got 30%, then 70% you missed. And therefore you can go back and look to see what might be needed to kind of go yourself, get yourself cleared on those issues, et cetera, et cetera. So this is not about testing you. I just want you to know that. That's not the agenda at all. It's really to be able to see what is it that you think you have learned so you can test it out. And if you haven't learned, then you'll be clear that it's not learned. And in some sense, we will also get a sense of how effective we were in offering this training course. If you do well, then we did well. If you don't do well, even we didn't do well. So just keep it in that kind of a relationship. Okay, so I'm going to open it up for some questions. So people who have raised their hand have a question, we're going to be touching upon some of you to see what kind of question you might have. Please, let's discuss totally today only about the material of testing, how the testing is done, how do you do testing, what's the outlook that you have, what is it that you want to accomplish out of the testing. Ultimately, of course, students have to pass some kind of an exam from the university. That's clearly there, that has to be done. There's no two ways about it. We have this freedom within our system that we do the lectures, we set the questions. So there's a, I think, you know, the challenge for you would be how do you take what is covered in the UGC syllabus, what you teach, and what kind of questions to be asking the students so that you can train them. Okay, so I'll open it up. We are at the SDM Institute of Technology, Karnataka, Dakshan Karnataka, yeah, please, question. We have one question, sir. We are planning to give project work to students. We are going to collect the wind speed and direction using anemometer. That's very expensive. We can't offer this anemometer for all the students, so it's relatively expensive. Is there any small project in IIT, small anemometer-like devices, to study the wind direction and the wind speed? Okay, so good, okay, it's just fabulous that you're doing these projects, it's really great. You really, I don't think even we have an anemometer for every student. We just have one anemometer, and then students actually can take turns. We actually have students go and shift, especially, I should tell you, we do this every autumn semester we do this. We actually, in a class of 30, 35 students, by the way, the lab course is running parallel to the course which we are doing, which is an air pollution course, okay? So the things that they learn over there get actually implemented or manifested during the lab course. So one of the things we do every autumn semester is, sometime near Diwali, October sometime, is we choose two locations on campus. One location is very near the main road where the traffic is, and another one is out near the Jim Khanna grounds where the pollution levels are very low. And we actually have two high volume samplers, and we have students go in shifts of eight or four, okay, depending on the number of students, and we do eight hour shifts. So students actually start the measurements on Thursday night, and then they take shifts, and of course they are responsible about the classes to be attended and all that stuff. So Friday, Saturday, Sunday, okay? Friday is a working day, Saturday sometimes is a holiday, sometimes is not a holiday, Sunday is a holiday. So they can actually see the influence of traffic on a working day versus non-working day at the main junction, whereas what is the influence of that in the quieter Jim Khanna grounds, okay? Now while they're doing this, we also have them do the anemometer readings. So anemometer, we just have one anemometer, so we actually get them to do the anemometer readings and to see if they can correlate that if average concentration around the traffic junction was high during this eight hour period, the effect of that was seen a little later on the Jim Khanna grounds because the wind was in that direction, or it was not seen because the wind was in the other direction, okay? So those are some of the things we do. We also have an optical particle counter which gives us resolution at a one minute level. So that way we can figure out, you know, if the wind actually had an influence or not. The other thing I want to point out, and I appreciate the whole aspect of cost, okay? But I'm actually inviting you to start looking at some proposal where you would have a simple high volume sampler, one mini wall, and one anemometer. The whole thing put together would probably not be more than 10 lakhs, okay? And there would be agencies that are willing to sponsor your college to set that up, okay? You should make a effort towards that. However, the other side of it is that there is now virtual instruments that are available, okay? These are being not just, you know, 10 lakhs is also a sizable amount of money for any institute, and that is something that is experienced also by developed countries, okay? So what some universities have actually done is they've developed virtual instruments. So you can actually, other than, you know, YouTube, et cetera, et cetera, these are virtual instruments that you will see on the screen as though you were interfacing your computer, your laptop with the instrument, and you can actually control the entire instrument and the data acquisition, et cetera, from just by using your mouse on the screen, okay? So these are available. I'll send you at least a couple of examples. For example, I know for sure that Professor Viswas's group had developed this optical particle counter, okay? This is something which it actually looks like the panel of that instrument, and you can actually select, you are now sampling tobacco smoke. You click on that, and that instrument will actually begin to show on the screen what tobacco smoke, particle size distribution would look like. Or then you can pick up road dust, and you click on the road dust, and it'll give you the size distribution that would be expected from. So, you know, just having, it's like a pilot's cockpit simulation, okay? That's what it looks like. Like NASA people would be getting trained. Something similar. One of the limitations that we have a lot of times experiences when we're doing this course in the remote center mode, is that how do you do lab, okay? So virtual instrumentations are a very good way of approaching this whole issue. One last thing I want to say, and then I'll move to the next center. One time when we were doing the air lab, the next, the students who have done the air lab, they next time come to you for their MTech project, and you realized that they really didn't learn much in the lab, okay? Not enough to be able to now do research on their own. So we then said, listen, the experiments that we are doing are not training the students to do research. So if you really wanted them to get trained to do research, what kind of experiments, what kind of laboratory experiments would you give them? So we put away the old manual, we put it aside, and we said, okay, let's just think of something. So one of the questions we asked in the class itself was, what would students want to do? And we came up with different questions, and ultimately they decided they were going to find the length of a flame, of a candle, okay? The height of the candle flame, depending on how much oxygen is in the air. So normal air, if you take, you see a normal candle, it has a certain length. If I increase the amount of oxygen in the air, would the length of the flame increase or decrease? So we then had to develop an entire setup in which you took nitrogen from a cylinder, you took oxygen from a cylinder, you has rotameter for this, you have rotameter for this, and then you mixed it so that your proportion varied all the way from 100% oxygen to 10% oxygen. So under different oxygen nitrogen ratio conditions, we actually looked to see what is the height of the flame. Now you should just know that we spent a whole semester on this, and by the time we done with the semester, we had completely failed at that experiment. Why we know we failed was because we said, let's try and run this experiment with total 100% oxygen, okay? And the moment we did that, oh it was a sight, it was beautiful actually, that the flame was so hot, it ran right through the candle, melted the entire candle, and we had to suddenly stop all the oxygen and nitrogen supply, oxygen supply, because there was suddenly a fear of there would be fire. Be careful when you're dealing with flames, et cetera. But the process people actually learned how to measure a flame using a camera, how to use valves and regulators on a cylinder, what kind of pipes that are needed to connect. They went to the workshop and actually got a little chamber made in which oxygen and nitrogen would get introduced from two points. They made mistakes with that, the person who deals, the technician who deals with the, he came running to me and said, sir, these people are making mistakes. I said, let them make their mistakes, they will learn from their mistakes. You know, so the whole process quite exciting and you know, there's a lot of learning that happened over there. Now you know I get excited and I know it's already 12, 30. So I should stop over here.