00:01
The human eye is sensitive to wavelengths of light from about 400 nanometers to 700 nanometers.
00:06
And it wants to know what the energy range of the photons would be with this wavelength of light.
00:11
So, lambda 1, i call lambda 1 the 400 nanometer range, which i converted to meters and lambda to the 700 nanometer.
00:18
So to find the energies that are related to this, we simply use the energy wavelength relationship for light.
00:26
So we'll call this e1 for lambda 1 is equal to plank's.
00:30
Constant h times the speed of light c, since that's the speed at which photons travel, divided by lambda 1.
00:38
For plank's constant, we're going to use the value of the joules second planks constant into the electron volt second.
00:45
So it's 6 .626 times 10 to the minus 34 joules second.
00:49
And of course, c is three times 10 to the 8 meters per second.
00:52
Using this and plugging these values in, we find that this energy here, e, is equal to about 5 times 10 to the minus 19 joules.
01:06
So you'll notice from this relationship that the, we'll just do, we only have one digit here...