Potential Difference in Electronvolts?Watch
I am stuck on this question from the 2016 PAT test where the potential difference is given in electron volts. How do you solve this? The electrons are accelerated through a potential difference of 5.0 keV towards a fluorescent screen. What is the final speed of the electrons when they hit the screen? [You may assume that Planck’s constant is 6.0×10−34 J s, the speed of light is 3.0×108 m/s, the mass of the electron is 1.0×10−30 kg, and the charge on the electron is 1.6 × 10−19 C.]
When the electron moves through a potential difference of 5.0 keV, the change in potential energy is
5.0 kV × (1.6 × 10−19 C)
Using conservation of energy
Change in potential energy = Gain in KE
would allow you to find the speed.
In that case, take it that the elections gain 5keV of energy. Then 1/2 mv^2 for v.
But then again, it's more likely that it's a typo. It is odd for a uni entrance exam