How to find max KE of electrons in photoelectric effect

In summary, the conversation discusses the frequency of light and the magnitude of a VA (possibly referring to the work function of a metal) expressed in volts. The speaker is trying to determine the maximum kinetic energy of ejected electrons and is using the formula E = hf to calculate it. They mention that the work function needs to be converted to energy in Joules and that it represents the energy needed to release electrons, with any excess energy appearing as kinetic energy of the ejected electrons.
  • #1
smarton
1
0
The information I'm given is:
frequency of light: 9X10^14 Hz
magnitide of VA 1.3 V (not sure what this is, maybe stopping potential?)

It says to simply state the max KE of the electrons so it must be quite simple but I just don't see it. I tried E=hf but this doesn't give max KE. Must have something to do with the 1.3 V.

Thanks for your help.
 
Last edited:
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  • #2
Using E = hf gives the energy of an incident photon of radiation. You are on the right track.
I assume VA (?) is the work function of the metal (expressed in volts) which must be converted to an energy in Joules.
The work function is energy that must be removed from the incoming photon energy to JUST release electrons, any excess appears as KE of ejected electrons.
Hope this helps
 

FAQ: How to find max KE of electrons in photoelectric effect

1. How does the photoelectric effect demonstrate the concept of maximum kinetic energy of electrons?

The photoelectric effect is a phenomenon in which electrons are emitted from a metal surface when it is exposed to light of a certain frequency. This demonstrates the concept of maximum kinetic energy as the electrons that are emitted have a maximum kinetic energy dependent on the frequency and intensity of the incident light.

2. What factors affect the maximum kinetic energy of electrons in the photoelectric effect?

The maximum kinetic energy of electrons in the photoelectric effect is affected by the frequency and intensity of the incident light, as well as the work function of the metal surface. The work function is the minimum amount of energy required to remove an electron from the metal surface.

3. How can the maximum kinetic energy of electrons be calculated in the photoelectric effect?

The maximum kinetic energy of electrons can be calculated using the equation KEmax = hf - φ, where h is Planck's constant, f is the frequency of the incident light, and φ is the work function of the metal surface.

4. Can the maximum kinetic energy of electrons be greater than the energy of the incident light in the photoelectric effect?

No, the maximum kinetic energy of electrons cannot be greater than the energy of the incident light in the photoelectric effect. This is because the energy of the incident light is used to overcome the work function and any excess energy is converted into kinetic energy of the emitted electrons.

5. How does the maximum kinetic energy of electrons in the photoelectric effect relate to the stopping potential?

The stopping potential is the minimum potential that must be applied to a metal surface to prevent the emission of electrons. The maximum kinetic energy of electrons can be used to calculate the stopping potential using the equation Vstop = (KEmax)/e, where e is the elementary charge. As the maximum kinetic energy increases, the stopping potential also increases.

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