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Practice Problem

Posted: Sun Apr 15, 2018 3:51 pm
by Fiona Grant 1I
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.

A. What is the kinetic energy of the ejected electron?

For this problem, I want to use the equation E(k)=(1/2)(m(e-))(v(e-)^2) to find kinetic energy. The velocity, but not the mass, of the electron is given. How should I go about solving this?

Re: Practice Problem  [ENDORSED]

Posted: Sun Apr 15, 2018 3:52 pm
by Natalie Noble 1G
You are correct to use the formula


The problem gives you the velocity of the electron and you don’t need the work function they give you for this problem.

The mass of an electron is a constant and it is:

9.10938 x 10^-31 kg

Now you have all the parts for the formula and all you need to do is plug them in.