Photoelectric Effect: Photoelectron Kinetic Energy vs. Frequency Graph

[5hassay]

Homework Statement

A graph displays the kinetic energy of photoelectrons as a function of frequency of light falling on a cathode in a photoelectric cell. If the cathode is replaced with one of greater force of attraction to its electrons, describe how a graph of kinetic energy against frequency (like the former) for this would be similar and different to the former graph.

Homework Equations

None (that I know of).

The Attempt at a Solution

For similarities, they would share the same slope. This is true because it is known that Planck's constant h is the slope of such a graph.

For differences, they would have a different threshold frequency. This is true because it is known that greater threshold frequencies are required to eject electrons (produce photoelectrons) for materials that have a greater force of attraction on their electrons in comparison to ones with lesser attraction.

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Personally, I feel that what I have said is true, but I might be leaving out important things that are worth the marks. So, any confirmation on my statements, the suitability of my answer for this question, and or help to direct me in the correct direction would be much appreciated.

:)

 

[ehild]

You are on the right track but there is an equation that explains that graph. It is conservation of energy, see http://www.walter-fendt.de/ph14e/photoeffect.htm
The photon gives its energy to the electron. What is the energy of the photon? To escape from the "potential well" of the metal, some energy is used, (it is the "work function" of the metal) and the remaining energy will be the KE of the escaped electron. Greater force of attraction means a deeper potential well, larger work function. ehild

 

[5hassay]

You are on the right track but there is an equation that explains that graph. It is conservation of energy, see http://www.walter-fendt.de/ph14e/photoeffect.htm
The photon gives its energy to the electron. What is the energy of the photon? To escape from the "potential well" of the metal, some energy is used, (it is the "work function" of the metal) and the remaining energy will be the KE of the escaped electron. Greater force of attraction means a deeper potential well, larger work function.


ehild

Ah, thank you very much. I do understand. Also, thank you for that link!