# Photons Emitted by the Sun

## Homework Statement

The sun emits 3x1032J of energy every day. Assume it emits only yellow light (6x10-7m wavelength. a. What is the energy of each photon of yellow light? b. How many photons does the sun emit every day?

E = hf

## The Attempt at a Solution

So I think I have question A complete, my solution is the following.
F = (3x108 m/s)/(6x10-7 m) = 5x1014 Hz
H = (6.6x10-34Js)
E=h*f (6.6x10-34Js)(5x1014Hz) = 3.3x10-19 J
Or E = 2 eV

But problem B I am stumped. I don't even know where to begin to figure this out. Can anyone help put me in the right direction?

## Answers and Replies

lewando
Homework Helper
Gold Member
You computed the energy of a single photon in J. You have the total energy output of the sun (n photons) in a day also in J. You seem pretty close to an answer.

So the answer is 9.9x1013 photons?

Redbelly98
Staff Emeritus
Science Advisor
Homework Helper
If you multiply 3x1032J and 3.3x10-19 J/photon, the result is 9.9x10^13 J2/photon.

Those units, J2/photon, do not make any sense. So no, that is not it.

Since the question asks for the number of photons, you're looking for an answer with units of "photons" in it.