## photoelectric effect question

Diego Gonzalez 3F
Posts: 32
Joined: Fri Sep 28, 2018 12:26 am

### photoelectric effect question

I understand that the energy of a photon minus the threshold energy to remove the electron from a metal surface is kinetic energy or Ek=1/2 M-V^2 but what does the kinetic energy equation mean? Why is there a 1/2 and what does the M stand for? why is the frequency squared?

Ricky Ma DIS 4E
Posts: 72
Joined: Fri Sep 28, 2018 12:27 am

### Re: photoelectric effect question

0.5 is just a parameter that is used in the equation. The M stands for mass of an electron which is a constant:9.10938356 × 10-31 kg. The V is this equation does not stand for wavelength but instead velocity. V^2 means velocity squared. Within the question, they should give you the velocity of the electron that was ejected.

Nicholas Le 4H
Posts: 74
Joined: Fri Sep 28, 2018 12:24 am

### Re: photoelectric effect question

Adding on to the earlier response before me, the formula, Ke=1/2mv^2, is just a physics formula we used to find the kinetic energy of a system. In this case, we are trying to find the kinetic energy held by the released electron that is left over after subtracting the energy given by the light source by the threshold energy a.k.a work function of the metal.