00:01
There are two sets of two radiations, i guess we would say.
00:10
So first we're asked, which has a higher energy, infrared radiation with a wavelength of 1 .0 times 10 to the negative 6 meters or an x -ray with a wavelength of 3 .0 times 10 to the negative 9 meters.
00:27
And so just intuitively, we should know that x -ray radiation, so radiation in the x -ray portion of the spectrum is going to be higher energy than radiation in the infrared spectrum.
00:45
We could also just look at these two wavelength values.
00:53
And so anything times 10 to the negative 9 meters is going to have a smaller wavelength than light with a wavelength given as 10 to the negative 6 meters.
01:09
And so since frequency more directly corresponds with energy and as wavelength decreases, frequency increases, we would expect the x -ray radiation to have the higher energy.
01:28
But to actually show this, we need to do some math.
01:32
And so i've written out at the top of the screen here, what we're going to need.
01:36
So this is first the equation that relates energy to wavelength and frequency.
01:45
So e equals hv, h being planck's constant, which i've also written out, 6 .62 times 10 to negative 34.
01:54
Joule seconds.
01:57
And we can also express this equation as energy equals hc over wavelength, over lambda.
02:06
And so that would be planks constant times the speed of light, which is the third thing that i've written out, 3 .0 times 10 to the 8 meters per second.
02:16
And so that is what we're going to use to solve this first part.
02:20
So we'll say e equals hc over lambda.
02:29
And then the pieces of information that we're given for the first part are the two different lambdas.
02:35
And so we'll have planks constant times the speed of light.
03:08
And so first we'll put this over the wavelength that we're given for the infrared radiation, so 1 .0 times 10 to the negative 6 meters.
03:24
And when we do this math, we end up with 2 .0 times 10 to the negative 19 joules.
03:36
Okay, so that's the energy of the infrared radiation here from the first part.
03:44
We'll just do the exact same thing over again for the x -ray radiation.
04:05
So, of course, this time, the value for lambda is going to be 3 .0 times 10 to the negative 9 meters.
04:25
And when we do this math, we end up with 6 .6 times 10 to the negative 17 joules.
04:38
Okay? and so the x -ray radiation is going to be higher energy.
04:44
And we knew that intuitively, right? as i talked about at the beginning of this problem...