 Okay. So let's do this one. Determine the energy of a mole of photons with a wavelength of 1.2 times 10 to the negative 8 meters. So we've got the wavelength and we're going to have to figure out the frequency of this first to determine the energy. Okay. So in order to determine the frequency, we have to do this same problem again. Frequency equals C divided by wavelength. You might as well keep it in per second because you're going to have to use that to cancel out numbers when you plug it into the Planck's equation using Planck's constant. So Planck's constant, so that's going to be given to you. And of course of Godro's number will be given to you too. In this case, what are we doing dealing with photons? So this is photons per mole. So what did we say? We want to determine the energy of 1. Yeah. Which one? H. H. This is Planck's constant. This is going to be given to you. Okay. Yeah. So have you guys gone over Planck's equation yet? Yeah. Okay. She has different units on it. Yeah. So joules second. Yeah. And then you're going to convert that. This is the same thing. Okay. So joules second is the same thing as this. Joules second is just second squared. Joules is meter squared, telegram second squared times seconds. So seconds divided by second squared is second. Does everybody understand what I'm talking about? Yeah. Okay. So I could do that. No, it's fine. Don't worry. Do you guys got it? Okay. So again, joules second is the same thing as this right here. Okay. So what do we got here? So let's write down. That's Avogadro's number. Avogadro's number. So we'll do it this way. Er, one second. So in this case, E equals NHB. Okay. So if we're doing it for one photon, N is one. And so when we do that, if we want to cancel out photons, we can think of this frequency of one photon, too, if you want to go so far as to cancel those units. I guess I should have thought about that. Okay. So would you expect this to be a big number or a small number if it's only one photon? Small, right? Small. So we got a big number. Then you probably have done something incorrectly. So 1.6, or I guess since we've got to do it to 266, 1.7 times 10 to the negative 17. And then like we were saying, meter squared, kilograms, second squared is joules. You guys need me to do that for you? Let's just do it. So meter squared, kilograms, second times second. Let me second squared like that. So that equals 1.7 times 10 to the negative 17. So if we wanted to figure out what the energy of one mole of these photons was, the only thing we changed is N to be MA. Is everybody okay with that? Should we calculate that one? Let's just calculate that one out since we talked about it at the beginning. Are there any questions on this one, ladies? Questions got it? Okay, can I raise this bottom down here? So instead of that, we're going to have 6.022 times 10 to the 23rd photons. So if you want to think of it. So we'll just take that number that we had before and multiply it by, in this case you should get a big number. So since you have to do it to 2 6 bigs, 1 2. Questions on this one? Yes, so yeah, so I mean I just had the answer stored in my calculator of these two times one, you know, and then so I just multiply it by avogadro's number in my calculator. But yeah, you have to multiply the thing all the way across to get that number. And you would expect it to be a big number, right, because it's a mole of photons at this point in time, right, as opposed to just one photon. Which would be a very small number. Is it possible that you can do it this way? Yeah, so do it this way. It's so much easier. Just do it this way, you know, just do it this way. I didn't get that, but I don't know. Well, let's kill the video and check it out, okay?