Anyone know how to go about solving the following two problems?(adsbygoogle = window.adsbygoogle || []).push({});

- What is the minimum frequency photons need to knock an electron out of a copper target?

- If a beam of photons with 3 times the frequency of the photons from the first problem strikes a copper target, at what speed will the fastest electrons leave the copper?

Thank you.

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# Modern physics - photon problems

**Physics Forums | Science Articles, Homework Help, Discussion**