### Module Question 27.A

Posted:

**Sun Apr 08, 2018 3:03 pm**Hello! I had a little difficulty answering a question from the post-module assessment.

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. What is the kinetic energy of the ejected electron?

I know that to find the kinetic energy, you use the equation E(photon)-threshold energy. 150.6 kJ.mol-1 is plugged in for the threshold energy but where does the velocity go into the equation? Thank you!

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. What is the kinetic energy of the ejected electron?

I know that to find the kinetic energy, you use the equation E(photon)-threshold energy. 150.6 kJ.mol-1 is plugged in for the threshold energy but where does the velocity go into the equation? Thank you!