How Many Photons Are Emitted by a 100W Bulb per Second?

[Brammo]

Homework Statement

Estimate how many photons of visible light (500 nm) are emitted by a 100 W Bulb.

The answer on the sheet says approximately 10$^{20}$ photons/second

However when I work it out I get a slightly different answer.

Homework Equations

I used that 1J=1W/s or E=P/t

Also Energy of one photon is E=hf so if you had lots of photons you would $\Delta$E=nhf where n is the number of photons.

The Attempt at a Solution

I get 2.5$\times$10$^{20}$ photons/second

 

[G01]

You solved the problem correctly.