Finding the kinetic energy of an electron

[bear421]

Homework Statement

This is a basic photoelectric type question.

What wavelength of light is necessary to produce photo-electrons of speed 2 * 10^6 m/s with a magnesium target?

Homework Equations

KE = pf - phi

phi = 3.7 eV
h = 6.63 * 10 ^-34

The Attempt at a Solution

I don't know how to find the energy of an electron from the velocity. Once I have that I think I can figure it out

 

[bear421]

I think I figured it out! E = .5 * m * v^2

 

[ajclarke]

Your equations are right =]