Threshold Energy Question

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Threshold Energy Question

Postby Drake_Everlove_1K » Fri Oct 14, 2016 3:24 pm


So I am a bit perplexed by the following equation, which is apparently true in both instances:

hv = threshold energy

hv = threshold energy + 1/2mv^2

(1/2mv^2 = kinetic energy)

In the first equation, the energy of what is being solved for?
In the second equation, what energy is being solved for?

How are both equations true? The second one just adds a variable. I'm so confused how they can both be true.

Posts: 34
Joined: Wed Sep 21, 2016 2:56 pm

Re: Threshold Energy Question

Postby Junghyuk_Park_1I » Fri Oct 14, 2016 3:45 pm

The first equation is used when an electron has not been ejected with an exit velocity off of the solid metal once the light source hits it. The second equation is used when the electrons have been ejected with a kinetic energy (which implies velocity). Basically, both equations are talking about the same thing, just different situations (electrons being ejected and not ejected). I hope this helps!

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