The closest stars are 4 light years away from us. how far away must you be from a 854 khz radio station with power 50.0 kw for there to be only one photon per second per square meter? assume that the photons spread out spherically. the area of a sphere is .

The distance from the radio station is 0.28 light years away.

Solution:

As per the question:

Distance, d = 4 ly

Frequency of the radio station, f = 854 kHz =

Power, P = 50 kW =

Now,

From the relation:

P = nhf

where

n = no. of photons/second

h = Planck's constant

f = frequency

Now,

Area of the sphere, A =

Now,

Suppose the distance from the radio station be 'r' from where the intensity of the photon is

Now,

We know that:

1 ly =

Thus

i think the answer is a, hope this is right, that would be my best guess.