00:03
Our question asks, how far away must you be for a frequency of 650 khz radio station with a power output of 50 kilowatts, which is our energy per unit time, must you be in order to experience only one photon per second per square meter? so for that, we are going to need to use our flux equation, which is our number of photons divided by our surface area.
00:40
And we are trying to solve for r, the distance you must be away.
00:43
So we can bring r squared up and flux down to the bottom of the fraction times 4 pi.
00:53
Now, this n value is our number of photons.
00:57
Our photons can be found by finding the energy associated with our frequency using planks constant, joules times seconds frequency to find our energy which is 4 .3 1 times 10 to the negative 28 joules and this is the energy per photon again the number of photons is our energy at the bottom of our fraction and at the top our power output which again was 50 times 10 to the negative sorry to the positive 3 and this is joules per second.
01:58
So this is going to be our number of photons per second, which gives us a value of 1 .16 times 10 to the 32 photons.
02:13
And again, we can use that value for n to find r the distance away that you need to be to experience one photon...