Electron-kinetic energy and potential difference

Question

An electron with an initial speed of 5.50×10⁵ m/s is brought to rest by an electric field.

1. What was the potential difference that stopped the electron?
2. What was the initial kinetic energy of the electron, in electron volts?

Answer 1

Hello there, thank you for the question! The first thing you can immediately notice is that the problem asked you to identify the potential difference needed to stop the electron. If you recall the work energy theorem relates the change in the kinetic energy to the work done on the electron.

1. Use ΔKE = KE_Final - KE_Initial = q*ΔV
2. Thankfully, you already calculated the kinetic energy for the second question and all that is needed is to convert to electron volts using the conversion 1 eV = 1.609 x 10^-19 C

I hope this helped!