Photoelectric Effect Module Problem

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Nancy 1B
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Joined: Wed Sep 21, 2016 2:58 pm

Photoelectric Effect Module Problem

Postby Nancy 1B » Tue Jul 11, 2017 3:28 pm

Molybdenum metal must absorb radiation with a minimum frequency of 1.09 x 10^15 s^-1 before it can emit an e- from its surface.
A. What is the minimum energy needed to produce this effect?
Answer: 7.22 x 10^-19 J
B. If molybdenum is radiated with 194 nm light, what is the maximum possible kinetic energy of the emitted electrons?

I was able to calculate part A of the question by using E=hv. How do I go about solving part B?

Paul Wong1B
Posts: 25
Joined: Fri Jun 23, 2017 11:39 am

Re: Photoelectric Effect Module Problem

Postby Paul Wong1B » Tue Jul 11, 2017 3:55 pm

1. Use 194 nm, convert it to meters, and solve for frequency using c=wavelength x frequency
2. Use E=hv and solve for the energy. This energy is the energy of a photon that is radiated onto the surface
3. Next, use the formula E(kinetic) = E(photon) - E(threshold) to solve for the kinetic energy

Since the required frequency value that is given is the minimum amount, the kinetic energy value that you will find is the maximum possible value.

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