## VIdeo Module: Photoelectric effect question

$c=\lambda v$

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MedhaVallurupalli1F
Posts: 30
Joined: Wed Feb 27, 2019 12:15 am

### VIdeo Module: Photoelectric effect question

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.
Answer the following three questions.
A. What is the kinetic energy of the ejected electron?

How do we find this?

Yilun Ding
Posts: 31
Joined: Tue Jun 25, 2019 12:15 am

### Re: VIdeo Module: Photoelectric effect question

In this case, the kinetic energy can just be calculated from 1/2mv2 since we already have velocity and mass (from the constant booklet)

Leah farhadi 1F
Posts: 36
Joined: Mon Jun 17, 2019 7:23 am

### Re: VIdeo Module: Photoelectric effect question

We are given the velocity, so we can plug it into the equation (1/2)mv^2, plugging in the mass of an electron where m 9.109x10^-31. This would be the answer, however since they gave you the work function, you could find the energy of the photon by adding the kinetic energy you found plus the work function given.

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