00:01
All right, this is a fun question.
00:02
So people actually radiate electromagnetic radiation with a particular wavelength.
00:08
So what we need to know about all electromagnetic radiation is that its speed, which is c, the speed of light.
00:17
It's all electromagnetic radiation travels at the speed of light is equal to the radiation's wavelength times the radiation's frequency.
00:25
So we've been told the wavelength of the radiation that people are emitting.
00:30
What we need to know is its frequency.
00:33
The frequency of the radiation emitted is then the speed over the wavelength, speed over wavelength.
00:41
That's equal to three times 10 to the eighth over, there we go, three times 10 to the eighth, over the wavelength, which is nine microns.
00:56
Now a micron is just a way of saying a micrometer, and micro means 10 to the minus.
01:04
6.
01:05
Let's make this clear.
01:06
This is 3 times 10 to the 8th over 9 microns, 10 to the minus 6...