 भ्व वाद्द,लगाद, किल एक लिए यो तर और रव, देखेगाद तूवाद यो वाद्द साथा, बीम में स़ाच्टा आप सदाच करनेवाच। आप स्झाद फूँ फूँ आप या कचीग वॎद्द बागर, बं वो साद्द करनेवाच थीजंवाच करनेवाच बना सीगावार अप्षेंटी के सीखावार वेड़ा सेखमने की साथ वेड़ा सीखावार ठीचो आउत द knees अफना कि क्यों मुझा सक्चिस क्यों छोगे दोगों ऽद पर दो वोड़ग करिरदा सेखमने कि सच्चिस के थी सच्छिस अद होगें which has infinite wavelengths there is no as in fixed wavelength that only this wavelength will come out it's a continuous so it has infinite wavelengths all wavelengths are possible so incandescent electric lamp has that property it produces a spectrum of continuous emission nature what about third third question in fact we have done in the class itself can you try this out no one third question should I wait or solve wait or should I solve ok so on the day I saying third that's correct fine let me solve this question now you have n number of turns that is wound tightly in a form of spiral with inner radius and outer radii a and b respectively when a current of strength i is passed through the coil magnetic field at the center is asked so let's say this is the bigger circle and that let us say is the smaller one ok inner radius is a and outer radius is b alright so within a width of b-a total number of turns are capital N fine now the problem is that I know the magnetic field due to a ring right magnetic field due to a ring is mu naught i divided by 2 r ok but then but then these are like multiple rings are there ok and different radii so you can't use the direct formula so you have to take the help of integration alright so at a distance of small r at a distance of small r you assume a ring of width dr ok pardon my drawing so at a distance of r I am assuming a ring of width dr so if it is at a distance of r magnetic field will be this if it is only one turn ok but if there are some number of turns which is let's say you know N1 then magnetic field with this now in this width of dr how many number of turns are there number of turns per unit width is N divided by b-a this into width of the ring dr this is N1 ok or you can write this as differential element you can say that this into dN this is dN ok number of turns so it will be mu naught i divided by 2 into N divided by b-a ok multiplied by dr by r this is the magnetic field because of the ring this one total magnetic field will be integral of that and the value of r goes from a to b when you integrate dr by r you get ln r ln b- ln a which is ln b- b by a that's option number 3 now these kind of questions people already solve and then go and take the exam so they already know most of the time the direct answer this is a very common question alright we will go to the next these three questions solve one by one and answer you can answer one by one ok fifth one the answer is 3 fourth one the answer is 2 see this is how you have to solve this question you have a ray of light that is incident at an angle of 60 degrees so this is the incident angle 60 degrees what will happen to this it will reflect off follow law of reflection and this angle will be 60 degrees what is asked is angle of deviation so angle of deviation is this much so 60 plus 60 plus this angle should be equal to 180 degree because this angle this line is straight line so that's why it is also 60 degrees fifth electric potential is given as this you need to find electric field now we know that electric field along x direction is minus of dv by this is partial derivative of v-2x so this is minus of 6x and when you put x equal to 2 you will get minus 6 sorry you get minus 12 option 3 is correct for fifth now solve question number 6 feel free to refer to your notes this is not the test you are writing feel free to refer to any formula, equation whatever notes you have you can do that samdara has answered sixth note samdara that's not correct remember this fringe width is how much lambda d by small d directly fringe width is given 0.3 mm so it remains 0.3 mm but fringes will shift fringe width will not change fringes will just shift understood everyone any doubts till now quickly type in let's move to the next one these three you can solve one by one first solve question number 7 let's discuss it and then we will solve going forward next question seventh near a server loop of conducting wire as shown electron moves along a straight line the direction of induced current will be lost now electron is moving in this direction so current is in opposite direction and if current is like this if current is like this the magnetic field will come out of the loop understood fine so what will happen is that as this electron moves away and away from here the change in flux also changes getting it if it is nearby the rate of change of flux when it is just passing this center when it is coming towards the loop the rate of change of flux is positive when it is going away from the loop rate of change of magnetic flux is negative so rate of change itself is changing so that's why it is variable when flux is changing then only induced current will be there so depending on what is the rate of change of flux induced current will show its behavior eighth one this one there is already answered others quickly answer hydrogen atom from excited state comes to the ground state by emitting a photon of wavelength lambda if r is a rickbook constant then you know that 1 by lambda is rickbook constant 1 by n1 square minus 1 by n2 square this you know so if wavelength is lambda so 1 by lambda is equal to rickbook constant r it comes to the ground state so 1 by 1 square that is 1 by 1 minus 1 by n square so from here you will get small n to be equal to this what about ninth during the formula of magnetic dipole moment how much it is magnetic dipole moment formula is what n i a it is n i a so it doesn't depend on the magnetic field in which it is lying it only depends on current area and number of turns so option 4 let's go to the next it's a theoretical question option 4 is correct if it is unstable if it is just unstable it doesn't need outside potential difference to create the laser but you need potential difference or current through it right sorry just one second it is metastable to ground state actually it I mean lower state is also ground state only but then ground when I say ground state after that it doesn't emit anything okay so metastable to the ground state where is 10th one from see 10th one is from communication system or you can say EM wave EM wave will be better it's from EM wave which is based on actually your general knowledge only okay right time to test your general knowledge whether you are going beyond the syllabus little bit anyways 11th okay others what is the answer for 11th of an infinitely long straight wire then a magnetic field is a thin walled pipe so basically it's a hollow cylindrical pipe current is flowing on the lateral surface okay current is flowing on the surface of it it will be zero inside the pipe okay you can imagine an ampere circuit a loop like this inside okay so you can write down b into b dot dl integral is equal to mu naught i that is passing through the loop current passing through the loop is zero so this is zero and because of the cylindrical symmetry b dot dl should be equal to b into 2 pi r where r is the distance at which you are finding the magnetic field so b has to be equal to zero fine so magnetic field is zero anywhere inside the thin walled pipe this is from your NCIT we have done this question in class also let's go to the next question it has four question one by one please solve anyone got okay 12th yes 12th is third correct so this is right so 1 by f will be equal to mu 2 by mu 1 minus 1 1 by r1 minus 1 by r2 okay so length is made of focal length in air so mu 2 is 0.15 so when you substitute in the formula 0.15 divided by it is oh sorry focal length is 1.5 so focal length is 1.5 in air 1 divided by 0.15 is equal to refractive index of the glass of the lens is 3 by 2 so in air mu 1 is 1 this minus 1 1 by r1 minus 1 by r2 okay and then we need to find out this focal length inside the water so 1 by f is equal to 3 by 2 divided by 4 by 3 now minus 1 1 by r1 minus 1 by r2 okay so these are the two equations 1 and 2 so if you divide it you will get f divided by 0.15 is equal to you know when you divide these two will get cancelled away so you can simplify and get the answer okay so 12th answer 3 is correct 2 sources are said to be coherent if they have the constant phase difference we have discussed this also explicitly in the class okay then 14th 14th you are saying 1 yes that is correct we have 3 registers 1 2 and 3 that are connected to form a triangle so is like this 1 ohm 2 ohm and 3 ohm the current sorry across 3 ohm the 3 volt battery is there so 3 volt battery is there like this we need to find the current through 3 ohm now if you find equivalent resistance the current through the equivalent resistance is same as current through 3 ohm because equivalent resistance will also be between these two points only so equivalent resistance will be 2 and 1 they are in series and that will be 3 so 3 and 3 are in parallel so 3 by 2 will become equivalent resistance okay so current will be 3 divided by 3 by 2 that is equal to 2 ampere option 2 is correct for 14 we are saying for 14 1 how okay I am sorry okay I was rushing actually sorry about that see the current through the equivalent is not equal to current through 3 ohm there are two different things current through equivalent will be sum of these two current i1 plus i2 current through equivalent will be this current alright so potential difference across 3 ohm is 3 volts so current will be 3 divided by 3 which is 1 ampere you are correct option 1 is correct for the 14 okay 15 in common emitter amplifier the input signal is applied across what yes base and emitter right fine so like these you can solve these four questions should we move to the next question any doubts quickly ask if you have any doubts please 1 by 1 16 and then 17 16 16 16 is saying 2 others see we know that number of nitrya after time t is n equal to n naught is the power minus lambda t okay and for the mean life t is equal to 1 by lambda you know this right half love is 0.693 by lambda and mean life is 1 by lambda so number of nitrya remaining will be n naught e to the power minus 1 okay so option 2 is correct that will be n naught by e is equal to n after 1 mean life so n naught by this will be equal to e 17 17 anyone do remember the lateral shift formula okay lateral shift is t sin of i minus r divided by cos of r this is what we derived right shift i is the incident angle r is the refraction angle refracted angle yes 17th is first just have to substitute the values over here okay and lateral shift produced is 1 by 3 for 1 unit of thickness so t is equal to 1 this is sin of i cos r minus cos of i sin r divided by cos of r okay so i is 45 degrees you can get the value of r so 1 by root 3 will be equal to sin of i minus cos of i tan r so sin of i is 1 by root 2 and then cos of i is also 1 by root 2 so you can get the tan r so tan inverse of whatever you get option 1 fine i will go to the next question okay alright so these are the next few questions you can solve them one by one we can discuss it one at a time okay 19th 1 28th 2 yes 98 1 is the answer 20th 2 is the answer oh sorry what i am doing you guys are solving 90th and 20th not the 18th 90th is 1 correct and 20th is 2 correct so Newton's for corpuscular theory was not able to explain why the light decreases its speed when it moves to the denser medium so if you apply that you will get it wrong so that's why wave theory is used to prove the refraction law isn't it the wave optics starts with the proof of the Snell's law 18th when material use in transformer must have high permeability and low hysteresis loss high permeability will make sure the magnetic field is higher and low hysteresis loss will enable lesser energy loss lesser power loss okay so these are 18, 19, 20th what about 21st 21st also you have answered potentiometer see how simple these this is actually CET paper whatever we have done in previous few problem solving session like last two problem solving session I was doing comet K so CET equations are relatively easier than comet K this is CET 2009 okay let's go to the next one solve these 22nd 2 the changes by what factor you know that the wavelength is h by p it depends on the momentum and momentum can be written in terms of kinetic energy as under root of 2M into K if kinetic energy is tripled the new wavelength वी वन of aluminum is row 1. वी वन of V1 of G. जी is MG force downward and upward direction. वे�स होँ पारचेगागागागागागागागा, वेप बूध यी, वेस आप वुझ की साथा. समच अखाच, वेप टी, वी की वी या जी, what does it mean correct so rho 1 v 1 g minus rho w v 1 g this is the net weight inside the water this should be able to rho 2 v 2 g minus rho water v 2 g okay now tell me which is higher v 1 is higher than v 2 is this correct difference in balancing yes that is what so listen here rho 1 v 1 g will be equal to rho 2 v 2 g okay minus of rho water into g v 2 minus v 1 okay now this aluminum is density of aluminum is less than the density of steel okay that you should know as general knowledge so volume of v 2 will be less than v 1 actually okay so v 2 minus v 1 will be less than 0 okay wait yeah sorry v 1 will be greater than v 2 find this tells us that v 2 minus v 1 is less than 0 okay so from here you can understand that this is more than that okay because there this thing will be negative quantity negative into negative will be positive so the mass of the mg of aluminum is more than the mg of steel by a factor of this so aluminum piece will be more when you weigh in here understood all of you i will go to the next question now these questions annihilation means that you have converted the mass into energy kilowatt hour kilowatt hour the unit of energy is kilowatt hour kilowatt is the unit of power okay so for 25th one microgram of matter is 10 raise to power minus 3 sorry minus 6 actually okay minus 6 how much energy it will release mc square that is 3 into 10 raise to power 8 whole square fine this much energy will be released and you should know what is 1 kilowatt hour equals 2 if you know it in terms of joule you just divide this with that if you don't know it it is 10 square 3 into into number of seconds and r has 24 into 60 into 60 it's a good idea to remember how many joule one kilowatt hour has so this when you divide that you'll get the answer 25th answer 4 is correct i hope you are not using calculators 26th the thing has answered 1 26 the answer is 1 okay number of significant figures in these numbers we have to count so basically here you know after decimal 0 are counted okay so you can see that it has 1 2 3 4 and 4 is also counted so 5 so now between 1 and 4 we need to see which one you can see over here you have these 5 and these 2 7 so that's a option 1 for 26 27 beta decay means emission of electron from from a radioactive nucleus right with every radioactive decay happens from the nucleus only it's a phenomena of the nucleus okay electron do not take part 28th anyone answer 28th okay 28th yes 28th is first let's see how an electric heater rated 200 volts and 500 watt is connected to ac mains the current drawn by 8 is watt so you know you can simply multiply v and i and equate that to power we are assuming that this ac mains has the rated voltage only we have assumed that the 200 200 into i is equal to 550 this the values are not proper in the book they have assumed there's to be 220 volts fine so the there is some correction required in the question but anyway you i think you have understood how we can solve this question okay here is shriram okay let's go to the next question finally some mechanics questions so it is seen that in ct paper the mechanics questions are the later part of the paper the first part is mostly class 12 syllabus so usually this is what is seen it may or may not happen again but just that i'm telling you and usually all class 12 syllabus questions are together and all class 11 syllabus questions are together okay pratik has answered 30th before answering anything else that's a good strategy you should look at the you know you can understand 30th is you know smaller question so it's a good strategy to answer the easier ones first 30th the moment of inertia of circular ring of a radius r and mass m about the diameter is mr square by 2 that's correct okay you can use the perpendicular axis theorem about this axis the moment of inertia is mr square so that is equal to sum of moment of inertia about these two and due to symmetry both of them are equal so about this one axis it will be half of about this axis anyways other questions 29 and 31 others are not answering what happened are these difficult let's see 31st question a body of mass 0.05 kg is observed to fall with an acceleration of 9.5 meter per second square the opposing force of air on the body is what so we know that the force due to gravity will be mg okay and there will be an opposing force let's say that is fo okay so net force is what mg minus f0 this should be equal to mass time acceleration which is 9.5 okay so f0 will be equal to m times g which is 9.8 minus 9.5 fine mass is 0.05 into 0.3 so it will be 0.015 Newton 29th see you can see clearly by the time you guys were answering one question others who have tried solving these two have answered these two question before you could even solve 29th okay so the learning is you don't need to go sequentially okay save time as much as possible anyways let's try to solve 29th a body of mass m moving along a straight line covers half the distance with speed of 2 meter per second the remaining half the distance is covered in two equal time intervals with a speed of 3 and 5 average speed is what we need to find out let's say distance is d so this distance is d by 2 and that distance is d by 2 okay so this distance is covered with 2 meter per second all right now from here to here you have two different speeds 3 and 5 okay so it says that the total time can be divided into two equal parts let's say from here to here total time is capital T so this is t by 2 and that is also t by 2 okay in equal time intervals these two distances are covered with the speed of 3 and 5 okay we know that the average speed of the entire journey is total distance by total time taken let's say total time is t0 okay so can you get the you know here can you get the value of t in terms of d by 2 in terms of d and velocity try getting it okay so let's try to solve now see here the first part the velocity is 2 meter per second sorry 3 meter per second and the next part it is 5 meter per second okay let's say time interval is t by 2 so t by 2 into 3 plus t by 2 into 5 this should be equal to d by 2 right total distance so from here you can get the value of t is equal to d by 8 okay so average speed is total distance d divided by time so from here to here the time taken is d by 2 divided by 2 plus total time from here to here is t which is d by 8 okay so you can see that d get cancelled away fine and you will get it as 1 divided by 1 by 4 plus 1 by 8 that will be 32 by 12 4 3 is a 2 8 by 3 okay 8 by 3 option 1 is correct fine let's move on this is from chemistry colloidal solution we'll leave this 33 33 and 34 okay 33 is saying third 33 answer yes 33 answer is third scattering is happening our intensity reduces in the direction of the lens next one 34 anyone no one the answer is 2 it can balance only when it can balance only when all of them are acting along one straight line okay but three neat one acts like this two and one act like that then only it will be balanced okay otherwise you know some of two sides of the triangle will always be greater than the third side if you add them vectorally it will follow the triangle of addition right so they should add up to zero fine we'll go to the next one all these prathik is martyr and suddenly we founds one quick question to solve okay let's go one by one over here sound wave transfers what momentum or energy or both let's see what is sound wave sound wave is a longitudinal wave where suppose these are the particles okay let's say this particle starts oscillating then it will make this particle also start oscillating then this particle also starts oscillating so like this the all the particles slowly slowly oscillate as the wave travels in this direction okay and if this particle suddenly increases its amplitude then everywhere the amplitude will be increased correspondingly and if velocity increase everywhere the velocity will be increased correspondingly okay so the energy is the wave and the momentum is the particles velocity which is coming in as the wave move forward okay so both energy and the momentum gets transferred okay 37 is gp thompson experimentally confirm the existence of matter wave by phenomena of diffraction okay this you should know it as a fact okay now 36th read the question and solve anyone 36 should i solve what is the condition for maximum compression when the maximum compression will happen what do you think at a maximum compression what happens how to identify it see this is this has velocity this has no velocity okay so initially what will happen this block will come closer to b okay then slowly and slowly b will gain the velocity all right but then it will keep a will keep on coming closer to b till the velocity of b let's say vb becomes equal to velocity of a okay so condition for maximum compression extension is that their velocities are equal then only they will stop coming closer to each other or stop going away from each other okay now let's say this is equal to v all right so if we have assume these two as one system okay the momentum will be conserved or not tell me momentum will be conserved in horizontal direction or not it will be conserved even though spring is there because spring is because spring is applying a force which is internal to the system spring is a part of the system okay the mass of a which is two into its velocity this is the momentum initial momentum this will be equal to two plus three into the final velocity because final velocity is same for both of them from here you get velocity and then you apply conservation of energy or work energy theorem u2 plus k2 minus u1 plus k1 okay w is 0 u1 is 0 k1 is half mass of a is 2 into 0.15 square k2 now both the masses are moving in the same velocity so that is 2 plus 3 into v square and u2 is half kx square solving this equation you get the value of x which is the answer understood all of you any doubt let's go to the next question okay others we are going to use r equal to r not 1 plus alpha delta t okay r is 0.6 this is equal to 0.3 1 plus alpha is 1.5 into 10 is power minus 3 delta t okay so from here you will get the value of delta t all right delta t is equal to final temperature minus 300 kelvin fine so you will get the value of final temperature remember you will get the final temperature in kelvin because you have written 300 is as kelvin okay so option number 2 is correct when you solve 49 1 the work done by the force on a body as shown in the graph total work done in converting an initial in converting an initial distance of 20 meters covering the initial distance of 20 meters will be what the area under the graph okay so area till here this area is the work done because integral of f dr this is the work done and mathematically this is nothing but area under the force and displacement curve okay so you can connect this point like this and divide it into a trapezium and a triangle okay you get the value of area 39 answer 1 is correct 40th 40 resolution formula is required over here if you don't know please refer to the book similar question we have solved in last problem solving practice the formula is this theta is the angle of resolution minimum angle of resolution this is given as 1.22 lambda by d d is the you know diameter of the aperture which is your eye only in this case okay and theta is what theta is this angle suppose you are viewing two small objects from very far this is your eye okay the angle subtended by these two points this is theta okay and how you find this theta if this distance between the two point is d and this distance is let's say l theta is equal to d by l okay where d is a distance of separation so d divided by the length which is 10 kilometers that is 10 is power 4 meters this is equal to 1.22 lambda is 500 nanometer that is 5 into 10 is power 7 meters divided by aperture which is 2.5 into 10 is power minus 3 okay so you will get 2.44 meters fine let's go to the next question solve these okay 41 two different answers for 41 a door of 1.5 meter wide requires a force of one Newton to be applied at the free at the free end to open or close it the force that is required at a point 0.4 meter distance from the hinges for opening or closing the door is what now opening and closing of the door is nothing but rotation of the door right so torque should be equal in both the cases because angular extension should be same to open it so basically if it is 1.4 meter wide one Newton the torque applied is 1 into 1.6 this should be equal to torque applied by the force which is 0.4 meter away okay so the force will be 4 Newton option 3 43rd spectral lines of hydrogen atom that lies in visible region of electromagnetic spectrum is bomber series right bomber was a teacher in a school who has conducted several experiment because of lack of instrument he could do only for the visible spectrum so he came up with the first set of spectrum that is bomber series okay 42nd 0.1 meter cube all right anybody else solve 42nd yes on that that's correct 0.1 meter cube of water at 80 degree Celsius so 0.1 meter cube at 80 degree Celsius is mixed with 0.3 meter cube at 60 degree Celsius you need to find the final temperature okay so basically what will happen is that this 80 degree Celsius will lose the heat and 60 degree Celsius will gain the heat okay definitely it can it can't be 60 right because temperature will lie in between and the more volume is with 60 degree Celsius so answer will be closer to 60 it can't be 70 it would have been 70 if equal volume mixed then it will be the average of these two it can't be 75 because 75 is closer to 80 but with 80 the volume is to answer will be 4 only let's see how to do this so let's say mass of this is m so mass of that will become 3 times m right so 3 m into specific heat into t minus 60 this should be equal to m into specific heat into 80 minus t m into s so you'll get 3t minus 180 is equal to 80 minus t so t will be equal to 240 divided by 4 260 divided by 4 which is 65 okay so like this you can solve this question any doubts till now anything fine let's go to the next set let's solve these two questions then we'll take a break okay a graph of pressure versus volume for idle gas a different process as shown in the graph curve o to c represents what o to c can be adiabatic or it can be isothermal okay and we know that adiabatic process has steeper slope that's our option 3 or 44 what if if correct it will be 1 frequency of e m wave doesn't change if it goes from one medium to another fine all right so let's take a small break okay i'll just change the slide if you don't want to take a break you can attempt these two questions so right now it is 12 15 we will meet at 12 13 all right so i can see most of you have already attempted question number 46 and 47 so i'll quickly solve this 46 is about a planet revolving around the sun in elliptical orbit the linear speed of planet will be maximum at we know that the equal area will be swept at equal interval time so if planet is away from the sun its velocity will be lower and closer to the sun its velocity will be higher so it will be highest at a okay so 46 option 2 is correct 47 a horizontal tube of non-inform cross section has radii 0.1 meter and 0.5 meter respectively at m and m for a streamline flow of liquid the rate of flow of rate of liquid flow should be same right it should be same fine this is continuity equation okay let's move to next question now these three okay 48th potential drop across capacitor and resistor is given we need to find the applied voltage so we know that these potential drops are phasors okay so we cannot add them like numbers so they are 90 degree out of phase isn't it so net potential is under root of 5 square plus 12 square which is 13 volts option 4 okay 49th what is the answer okay heat radiated by a metal at a temperature t is e when the temperature increase to 3t the energy radiated will be what so energy radiated is proportional to th power 4 isn't it so if from t to 3t it goes the energy radiated will be 3 raise to power 4 times which is 81 times e okay what about 50th sign here is already answered others the angle of minimum deviation for an incident light ray on an equilateral prism is equal to its refracting angle the refractive index of the material is what mu is equal to sin a plus delta m by 2 divided by sin a by 2 okay so basically delta m is equal to a only which is 60 degrees all right so you can get the value of mu to be root 3 sin of 60 by sin of 30 you will get understood all of you any doubts let's go to the next few questions these ones 51 option 2 is correct here 1 and 1 will become 1 and then not 0 and then not again 1 okay so 1 and this is this can be anything 0 or 1 the output will be 1 only okay so it can't be 1 and 4 and then look at the second one 0 and 1 there will be a 1 this is 0 and yet it will become 0 but there is a not also so it will be 1 that's our option 2 okay 52 what is the 52nd answer others a stationary point source of sound emits uniformly in all directions non absorbing mediums 2 points p and q are at a distance of 4 and 9 meter from the source the ratio of amplitudes of the wave at p and q is what so the ratio of amplitude a 1 by a 2 okay this is actually root of ratio of intensities okay and intensity is proportion to 1 by distance square fine so this will be like 1 by 4 square divided by 1 by 9 square right so you will get 9 by 4 option 3 understood all of you i will move to the next question okay by the way today's class i am going to extend by 15 minutes so we'll end at 115 okay because of the late start we'll end at 115 it's all these questions anyone a gallon meter of resistance 240 ohms allows only 4 percent of main current after connecting shunt resistance the value of shunt resistance is what you know that if you have a shunt resistance it is always connected parallel okay so if main current is i not this current would be 0.04 i not right gallon meter has 240 ohm resistance right so since these two are connected parallel let's say resistance is r over here we have 0.04 i not times small r equals to i not into 240 ohms fine sorry there is a small correction before shunt resistance was connected okay the gallon meter had the current i not after shunt resistance is connected gallon meter has a current of 0.04 i not this is what the thing is from here the current is still coming i not if shunt resistance would not have been there gallon meter would have got i not current but now it is getting 0.04 i not so this is what it means from here the current will be 0.96 i not all right so 0.04 i not into gallon meter which is 240 ohms this is equal to 0.96 i not into small r fine so from here you can get the value of small r small r is equal to 240 into 4 divided by 96 so 53rd the option number is 4 24 right 54 the phenomena in which 4 proton flips is what this again you should know it as a fact that is 4 55 what is the answer 55 anyone 55 this represent an equation of progressive wave t is in second and x is in meter the distance traveled by the wave in five seconds is what for that you need to know the velocity okay so omega by k is the velocity of the wave fine omega is 1 by 2 and k is 1 by 4 so speed of the wave is 2 meter per second okay so in five second it will travel 2 into 5 that is 10 meters actually omega is pi by 2 and k is pi by 4 pi is also there but then it again get cancelled 56 okay this is not in the syllabus leave it these two that विल सेवनाद ध्रफ्वर मप्तिड़िया दिश्व़। ती विल ती विल, मी अद्टीक कब आप औग़ा सेवन भी रहीत क्येगिगाति, का यह खबिम कि लग़्ारी बबअत वो आपुत हैएँ, when it starts from rest is what. So you can see that electric field is uniform. So acceleration will be equal to I will just give you a hint do not need to completely solve it on my end. Q into E is the force this divided by mass will be the acceleration. Mass of the alpha particle and distance is given we can say that it is a constant acceleration V square equal to u square plus 2a into distance 2as so from here you can get the velocity initial velocity is given when it starts from rest so initial velocity is 0 so V is equal to just under root of 2as find the correct answer is option 3 okay can you solve the 58th question now okay prepaid has solved cylindrical tube at both ends has a fundamental frequency of this much in air if 1 further tube is immersed vertically in water the fundamental frequency becomes what okay so we know that if it is open this will be the fundamental frequency isn't it if length is L then velocity of wave is V so V divided by wavelength is the fundamental frequency okay and wavelength can be written in terms of the length of the tube wavelength is L by 2 so this is 2V by L this is the fundamental frequency when both ends are open now if 1 fourth of the tube is immersed in water so it will act like a closed tube alright and the length will be 3L by 4 closed tube and this will be the fundamental frequency so 3L by 4 will become equal to lambda by 4 from here you will get wavelength to be equal to 3 times length right correct so the fundamental frequency now will be velocity will not be changed velocity the medium is same here and there velocity will be unchanged so it will be equal to V divided by wavelength that is 3L so V by 3L so if you take a ratio of fundamental frequency earlier and now I will get 6 so 1 sixth of the earlier fundamental frequency actually here it will be 2L earlier wavelength was 2L sorry about that so this is 2L so when you take a ratio it will be 3 by 2 right so mu not dash the new frequency is 2 third of the earlier frequency so it will be 1 3 0 into 2 260 understood any doubts please ask quickly we will go to the next one then these two questions what is the wings displacement law which tells us lambda into t should be a constant you can easily find out the wavelength received from far away star and multiplication of these two should be a constant that is what the wings displacement law is about okay now solve the 60th question okay with which we have answered others okay the correct answer is 2 only how we can solve this charge deposited on 4 mycloquorum capacitor is what is asked so if I know the potential difference between these two points I will be able to find the charge okay so let me first find the equivalent of these two which is 6 so 6 and 6 are connected in series across 12 so I know that if 6 is connected in series with another 6 this is 6 micro farad and there is another 6 micro farad let me not change the location this the 6 micro farad this one is equivalence of 4 and 2 parallel okay so since these two are connected in series Planck's law is about spectral density of em wave so it basically says that it will be under equilibrium with the surrounding the amount of heat the rate of heat it absorbs will be equal to rate of heat it emits okay in fact Planck's law expression is not in our syllabus itself so it gives you an expression of power emitted per unit area of the body the Planck's law for a particular wavelength okay but it will not tell you it will not let you compare between two bodies two black bodies where wavelength into temperature should be a constant temperature is that temperature for which you know the intensity of or the power emitted is the maximum because different wavelengths will be emitted so wavelength at which the power emitted is maximum that wavelength into the temperature of the black body should be constant this is Wien's Displacement law Planck's law is something else okay so what I was saying is since these two are connected in series the charges will be same so let's say q and q are the charges so I can apply the Kirchhoff loop rules of 12- q by 6 and will be another factor will come in this should be equal to 0 so you will get q as 36 micro coulomb fine once you get 36 micro coulomb you can find out the potential difference between these two points as in across 6 micro coulomb 6 micro farad sorry the potential difference will be equal to q by c 6 divided by 6 so 6 volts in fact you can make out from here also that 12 ohm back raise connected across two similar capacitors so half half it will be divided so 6 volt is the potential difference across these two points and across these two points only the 4 ohm is connected so charge on the 4 ohm capacitance will be equal to 4 into 6 that is 24 into 10 is called 6 coulomb fine so this is how you solve this particular question fine so today I have this much to cover only total 60 questions we have covered today tomorrow again we are meeting I think tomorrow tomorrow is again there is a class so tomorrow we will be covering this is ct 2009 paper tomorrow we will be covering k 2009 paper alright anyone has any doubt till now please type in any doubts alright friends so that's it for today we will meet again tomorrow I will announce the timings in the group sorry for the late start today would not help at times some technical problems but we have covered everything whatever was planned ok bye bye