## Equation for threshold energy

Haley Pham 4I
Posts: 51
Joined: Fri Aug 09, 2019 12:16 am

### Equation for threshold energy

How do we calculate the threshold energy, or the energy needed to remove an electron from a metal atom? What equation(s) would be used to calculate the threshold energy?

Sydney Jacobs 1C
Posts: 59
Joined: Thu Jul 25, 2019 12:15 am
Been upvoted: 1 time

### Re: Equation for threshold energy

The equation involving threshold energy is as follows: E(photon) - threshold energy (or work function) = Kinetic energy (or excess energy). If the energy of the photon is known as well as the excess energy, the threshold energy can be found. Threshold energy also follows the equation E(threshold energy)=hv, in which v is the frequency required to remove an electron.

Julie Park 1G
Posts: 100
Joined: Thu Jul 25, 2019 12:15 am

### Re: Equation for threshold energy

You can use...
1/2mv^2 = hv - work function

1/2mv^2 refers to the kinetic energy of an ejected e-
hv refers to the energy supplied by a photon
the work function (threshold energy) is the energy required to eject an electron