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### Photoelectric Effect Module

Posted: Mon Oct 15, 2018 10:06 pm
I had a question about one of the parts of the Photoelectric Effect Module Post Assessment.
Question 30 specifically. The given information is as follows:

Light hits a sodium metal surface and the velocity of the ejected electron is 6.61 x $10^5$ m/s. The work function for sodium is 150.6 kJ/mol.

The question asks for the frequency of the incident light on the sodium metal surface. So I began by solving for the energy of the incoming light by adding the work function to the energy of the emitted electron (answered in a previous question as 1.99 x $10^-19$ J. Once I had that energy calculation I used Planck's equation to solve for frequency and got 2.27 x $10^38$ Hz. Which was a multiple choice answer that was wrong.

I'm not sure how to properly solve this question and would appreciate any help! Thank you!

### Re: Photoelectric Effect Module

Posted: Mon Oct 15, 2018 10:18 pm
Before adding the work function to the energy of the emitted electron, you must first divide the work function by 6.022 x 10^23, as the work function is given in moles and you are looking for the threshold energy to remove a single electron. You must also then convert this number into joules from kJ so that your units are consistent.

### Re: Photoelectric Effect Module

Posted: Tue Oct 16, 2018 8:02 pm
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?

How would one go about to solve this problem?
What equation would be used?

### Re: Photoelectric Effect Module

Posted: Tue Oct 16, 2018 8:08 pm
Gabriela Aguilar 4H wrote: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.