What determines if the photoelectric effect occurs?

In summary, the photoelectric effect occurs when photons of a certain frequency are absorbed by the photo-cathode and eject electrons with a minimum kinetic energy. The energy of the photons must be greater than the work function in order for this to happen. The intensity of the incident light does not affect the individual kinetic energy of the ejected electrons, but it can increase the number of ejected electrons. The stopping potential is achieved when there is zero current in the circuit, and this can be achieved by changing the polarity. The photoelectric effect is a result of the dual nature of light as a wave and a particle.
  • #1
MRFISCHERRULZ
8
0
What determines if the photoelectric effect occurs?

There are several aspects on this topic that I don't really understand such as:

- What is the relationship between the frequency of the incident photon, threshold frequency and the ejection of electrons?

- What is the relationship between the energy of the incident photon, the work function and the ejection of electrons?

- What is the relationship between kinetic energy of the ejected electrons, the energy of the incident photon and the work function?

- What is the relationship between the intensity of the incident light and the average kinetic energy of the ejected electrons?

- What is the relationship between the intensity of the incident light and the number of ejected electrons?

Thanks
 
Physics news on Phys.org
  • #2
Forgot to include my work so far, please assist me if this is correct so far, thanks

1)The energy of a photon is a function of the frequency of the photon

Energy = (Planck's constant * Speed of Light) / wavelength = Planck's Constant * Frequency

If energy is large enough it will knock an electron loose

2) Any energy in excess of what is needed to knock an electron loose (Work Function) goes to KE of the electron

4) Not related the number of photons per second has no relationship to the KE of the ejected electrons

5) The more high energy photons you have the more electrons you knock loose
 
  • #3
MRFISCHERRULZ said:
Forgot to include my work so far, please assist me if this is correct so far, thanks

1)The energy of a photon is a function of the frequency of the photon

Energy = (Planck's constant * Speed of Light) / wavelength = Planck's Constant * Frequency

If energy is large enough it will knock an electron loose

2) Any energy in excess of what is needed to knock an electron loose (Work Function) goes to KE of the electron

4) Not related the number of photons per second has no relationship to the KE of the ejected electrons

5) The more high energy photons you have the more electrons you knock loose

You have posted down various doubts over the photoelectric effect ,I will try to be as concise as possible.

P.F.E. occurs when light of enough/over frequency* is absorbed by the electron of the photo-cathode end[often cesium] (note intensity has no direct correlation with individual photon energy),as a result of this electron is ejected but this happens when K.E is minimum.
Which can be found by the following equation:
EKmax = hf- w [w is the work function)
At min. K.E = 0
so hf = work function
What triggers this,I am not quite sure about but if I vaguely recall since Light acts both as a wave and particle,it has an E-M field which has oscillation,it's these oscillation which excite/kick the electron[Don't take this to be valid for I maybe wrong].
Also you may have not come across this yet but stopping potential is achieved when there's zero current between the circuit this is achieved by changing the polarity.
Just to remind you again intensity has no affect over individual K.E of electrons however if the no. of photons is increasing so does the no. ejected electrons which results in a greater current value between the circuit.
I hope this answers your doubts.
P.S: I think this thread should be under classic sub-section ? :s
-ibysaiyan
 
Last edited:

1. What is the photoelectric effect?

The photoelectric effect is a phenomenon in which electrons are emitted from a material when it is exposed to light of a certain frequency. This effect was first observed by Heinrich Hertz in 1887.

2. What determines if the photoelectric effect occurs?

The occurrence of the photoelectric effect is determined by two factors: the frequency of the incident light and the work function of the material. The frequency of the light must be equal to or greater than the threshold frequency of the material, and the work function must be overcome for electrons to be emitted.

3. What is the threshold frequency?

The threshold frequency is the minimum frequency of light required to cause the photoelectric effect in a particular material. It is a characteristic property of the material, and it varies depending on the type of material.

4. How does the intensity of light affect the photoelectric effect?

The intensity of light does not affect the photoelectric effect. The number of electrons emitted is determined by the frequency of the light and the work function of the material, not the intensity. However, increasing the intensity of light does increase the number of photons and therefore the number of electrons emitted per unit time.

5. What is the significance of the photoelectric effect?

The photoelectric effect has significant implications in modern physics, including the development of quantum mechanics and the understanding of the wave-particle duality of light. It also has practical applications in technology such as solar panels and photoelectric sensors.

Similar threads

Replies
5
Views
635
  • Quantum Physics
Replies
12
Views
733
Replies
5
Views
1K
Replies
10
Views
2K
Replies
13
Views
1K
Replies
5
Views
1K
  • Introductory Physics Homework Help
2
Replies
35
Views
1K
  • Quantum Physics
Replies
21
Views
1K
  • Quantum Physics
Replies
1
Views
894
Replies
7
Views
1K
Back
Top