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### Threshold energy

Posted: Thu Oct 11, 2018 12:36 pm
I have in my notes that (E=hv) - work function = (Ek= 1/2me-ve^2), however there was mention of threshold energy that I didn't quite understand. What is this threshold energy and how does it factor in to the above equation?

### Re: Threshold energy

Posted: Thu Oct 11, 2018 12:44 pm
I believe in this scenario the work function and threshold are interchangeable. So your equation can also look like this:

(E=hv) - threshold energy = (Ek= 1/2me-ve^2) or exactly like the one you posted. Threshold energy is the amount of energy it takes to remove an electron from a metallic surface, just like the work function.

### Re: Threshold energy

Posted: Thu Oct 11, 2018 12:52 pm
The threshold energy is defined as the amount of energy needed to remove an electron from a metal. This energy is called the work function (Φ), and their values are equivalent.

### Re: Threshold energy

Posted: Thu Oct 11, 2018 2:22 pm
The threshold value needed to remove an electron can be treated like any other requirement needed before an action can occur. A particle needs to have a minimum amount (varying on the type of substance) of energy in order for an electron to be ejected. Taking this into consideration, if we know how much energy the particle had before colliding, and threshold value required to remove an electron, then we can calculate the kinetic energy of the electron by this equation E-threshold energy = .5me-ve^2.

### Re: Threshold energy

Posted: Thu Oct 11, 2018 3:51 pm
In the case of this equation, work function (referring to the energy needed to be put in) and threshold energy (referring to the frequency needed to eject an electron) can be used interchangeably.

### Re: Threshold energy

Posted: Fri Oct 12, 2018 12:52 am
Threshold energy is the minimum amount of energy needed to eject an electron