Photoelectric effect and frequency

1. Sep 28, 2008

briteliner

1. The problem statement, all variables and given/known data

the wavelengths of visible light range from about 380 nm to 750 nm. what is the range of photon energies (in eV) in visible light? a typical fm radio station's broadcast frequency is about 100Mhz. what is the energy of an FM photon of the frequency?

2. Relevant equations
eVo=hf-(phi)
phi=hfo
i don't know how to get fo which is the threshold frequency. thats the only part im stuck with

3. The attempt at a solution
i don't know how to get fo which is the threshold frequency.

2. Sep 28, 2008

gabbagabbahey

The energy of a photon of frequency $f$ is given by $E=hf$.

$eV_0=hf-hf_0$ allows you to determine the difference in electric potential necessary to make electrons in a material with a threshold frequency $f_0$ to emit photons of frequency $f$. This equation is useless to you here. You are simply asked to determine the energies of photons of a given wavelength or frequency.