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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

E(k)=(1/2)(m(e-))(v(e-)^2)

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.