## Photoelectric Effect

Tiffany_Cacy_3D
Posts: 70
Joined: Fri Sep 28, 2018 12:24 am

### Photoelectric Effect

I am taking the post-module test for the photoelectric effect module and I am having trouble with number 28. So the information given is the velocity and the work and the work function. Because it is asking for the Kinetic Energy I assume you would need to use the formula E=1/2(MV2) but I am not sure how to get M in order to complete the question. Am I using the wrong formula? Any help is appreciated!
This is the question for context..
28. Light hits a sodium metal surface and the velocity of the ejected electron is 6.61 x 105 m.s-1. The work function for sodium is 150.6 kJ.mol-1.
A. What is the kinetic energy of the ejected electron?

caseygilles 1E
Posts: 73
Joined: Fri Sep 28, 2018 12:18 am

### Re: Photoelectric Effect

The mass of an electron is the same in each problem regardless of the metal that the election is emitted from. The mass of an electron is 9.10938356 × 10^-31 kilograms.

Meachelle_Lum_1I
Posts: 92
Joined: Fri Sep 28, 2018 12:24 am

### Re: Photoelectric Effect

Kinetic energy is calculated by 1/2mv^2. Use the given velocity in the problem and the mass of an electron (9.11*10^-31 kg), and substitute these values into the equation.