Figure $P 27.45$ shows the spectrum of light emitted by a firefly. (a) Determine the temperature of a blackbody that would emit radiation peaked at the same frequency. (b) Based on your result, explain whether firefly radiation is blackbody radiation.
November 16, 2020
right. So in this question, we have the spectrum of light emitted from a firefly. We want to get the temperature of a black body that would admit radiation picked it at the same frequency. So, um, let's find the peak frequency or wavelength. Um, so that looks like to me, I would say, I don't know, 500 and 60 Nana meters. Would you say so? What's right down Lambda Peak equals 560 nanometers. Fix up a six. Great. And then now we want to relieve that to temperature. So let's go hunt down the formula that we need for that. Is it in this chapter? Oh, yes. Itwas So it's Lambda Max Times temperature is 00.2898 And then I'll just stay with my peak notation So 0.0, was it 10 or two 0.2898 And this is just equation 27.1 point 02898 Cohen, uh, meters. And so if we want to sell for temperature, we just want to divide both sides by Lambda Peak. So I'll go ahead and just rearrange this formula. So I'm dividing out the Lambda Peak and bringing it to the other side. And then what I'm gonna do is plug and, um, lam a peak and then this number into my calculator and see what temperature? I got a point. Okay. 90 and then by calculator, I mean, my Google search are I pride myself on you Think the rest technology out there. So with that, I got um wow. So 5175 And how many sig figs we have in this problem? Uh, mojo. Well, maybe two for lucky. So let's say 5200 Calvin. Now, I'm gonna start using the approximation signs, because in such a big number, it's obviously not the temperature. Um, of what? What animal was that? It waas a church firefly. Um, so I would say no. This does not look like that. It would not be a good to model this fireflies of black Bonnie. Um, because fireflies air not 5200 Calvin. So you would subtract 2 73 to convert that to cells here, So they're not 5000 degrees Celsius. And so, um and so yeah, you would say it's not a black body