What is the Photon Flux for a 100 MHz Signal Traveling 4 Light Years Away?

[Ashley1nOnly]

Homework Statement

It's in attachment

Homework Equations

E=hf. Where h= planks constant and f= frequency

The Attempt at a Solution

I know that the flux of a photon is (# of photons)/(sec m^2)
I don't know the number of photos but I do know the frequency and power.

E=(6.6261*10^(-34)) J•s * (100 MHz)=6.621*10^-32
Also
Wavelength*frequnecy=c
I know that it's traveling 4 light years away.

Wavelength*(100MHz)=4c
Wavelength=4c/(100MHz

What equation am I supposed to use and how do I find the number of photon and how big in diameter would the recover/detector have to be. I don't want the answer just help understanding the problem and what I'm doing wrong. Or am I on the right track

Thanks in advance

 

[mfb]

The image has a wrong orientation.

You know the energy per photon, and the power. Can you get the photons per second, or per image frame?
To capture all photons in a distance of 4 light years, aliens would have to construct a sphere with a radius of 4 light years. They don't need all the photons, of course, but which fraction do they need?

 

[Ashley1nOnly]

I know the
energy is 6.621*10^-32
power is 100Kw 24 frames per second.

what equation should i use to relate them

 

[Ashley1nOnly]

I can do the power divided by the photon energy to get the number of photons arriving per second100 KW/ 6.21*10^-32

 

[mfb]

I can do the power divided by the photon energy to get the number of photons arriving per second

Right.
As every second has 24 frames, how many photons are there per frame?

All those steps all don't need fancy physics.

 

[Ashley1nOnly]

power divided by / ( the photon energy * 24) to get the number of photons per frame