Kinetic Energy of Electrons

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Kimberly 1H
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Kinetic Energy of Electrons

Postby Kimberly 1H » Thu Oct 11, 2018 10:38 pm

Why is it that the kinetic energy of ejected electrons increases linearly with the frequency of radiation?

Shubham Rai 2C
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Re: Kinetic Energy of Electrons

Postby Shubham Rai 2C » Thu Oct 11, 2018 10:44 pm

This is because the work function, or the energy required to cause an electron ejection is fixed. So, based on the equation E = hv, as the frequency increases, the energy of the photon increases. ANd because the work function is a fixed value, the remaining energy is transferred to the ejected electron, causing it to have more kinetic energy as the total energy of the photon increases.

Chem_Mod
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Re: Kinetic Energy of Electrons

Postby Chem_Mod » Thu Oct 11, 2018 10:45 pm

Essentially, it has to do with the conservation of energy principle. Frequency of light increases linearly with energy of that light. When the light's energy exceeds wave function, the energy that matches wave function will be used to remove the electron from the metal surface, and the extra energy will go into the kinetic energy of the emitted electron. Hence, the kinetic energy of ejected electrons increases linearly with the frequency of radiation. For example, let's say 5 J is the work function and the light has 6 J. 5 J from the 6 J will be used to eject the electron from the metal surface. The extra 1 J will be converted into that electron's kinetic energy. If the light's energy were 6.1 J, then the electron's kinetic energy would be 1.1 J. As you can see, they are linearly correlated, as changes in one are reflected exactly in the other.


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