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### VIdeo Module: Photoelectric effect question

Posted: **Mon Jul 08, 2019 11:58 pm**

by **MedhaVallurupalli1F**

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?

### Re: VIdeo Module: Photoelectric effect question

Posted: **Tue Jul 09, 2019 10:25 pm**

by **Yilun Ding**

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

### Re: VIdeo Module: Photoelectric effect question

Posted: **Thu Jul 11, 2019 9:38 am**

by **Leah farhadi 1F**

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.