Achieve (weeks 2,3,4) question 15

[juliaddc]

Hello!

Question 15 is: You use an electron microscope in which the matter wave associated with the electron beam has a wavelength of 0.0129nm. What is the kinetic energy of an electron in the beam, expressed in electron volts?

For this question I used the formula K=1/2 mv, which means I had to find v since it was not given. I was unsure whether to use λ=h/mv or c=λv , I ended up using (v=h/λm) and I got the units mixed up which caused me to get the rest of the problem wrong.
I know that my next step is to plug in v into k=1/2mv and then convert into eV, but I am stuck on the velocity.

Any help is appreciated, thank you!

[Caitlin Chen 3F]

I think your mistake is in your formula, v is squared in the formula so it should be K = 1/2 mv^2. Other than that, your process should be right.