Multiple choice conceptual question on the photoelectric effect

In summary, in a photoelectric effect experiment, increasing the frequency of light while keeping the intensity constant will result in a higher stopping potential for emitted electrons. This means that fewer electrons will be ejected from the metal surface. This is because the energy of each photon increases with frequency, causing a decrease in the number of photons per second striking the plate.
  • #1
Duderonimous
63
1

Homework Statement


In a photoelectric effect experiment, the frequency of the light is increased while keeping the intensity of the light constant. What effect does this have?

A) fewer electrons will be ejected
B) more electrons will be ejected
C) the same number of electrons will be ejected
D) any of these is possible

Homework Equations


None.

The Attempt at a Solution


I know that if the frequency of the incident light on the metal is increased this will cause the stopping potential of the electrons emitted to increase, whilst keeping the intensity of the light constant. If the intensity of the incident light on the metal is increased this cause the number electrons emitted per time to increase but the stopping potential remains the same.

So if the frequency is increased but the intensity is constant won't the number of electrons emitted be constant? I picked C but it was marked wrong. Can someone please clarify this. Thanks.
 
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  • #2
What happens to the energy of each photon when the frequency is increased?

What happens to the number of photons per second striking the plate as the frequency is increased and the intensity is kept constant?
 
  • #3
The energy of each photon is increased.

less photons per second but each photon is more energetic, thus fewer electrons are emitted but each electron has a greater stopping potential.
 
  • #4
Sounds good!
 
  • #5


Your understanding is correct. The answer should be C - the same number of electrons will be ejected. This is because the photoelectric effect is dependent on the frequency of the incident light, not the intensity. Increasing the frequency of the light increases the energy of the photons, which can then overcome the work function of the metal and eject electrons. The intensity of the light only affects the number of photons, not their energy. Therefore, as long as the frequency is constant, the number of electrons ejected will also be constant.
 

1. What is the photoelectric effect?

The photoelectric effect is a phenomenon in which certain materials emit electrons when exposed to light of a certain frequency. This effect was first observed and studied by Albert Einstein in 1905.

2. How does the photoelectric effect support the particle nature of light?

The photoelectric effect supports the particle nature of light by showing that light can behave like a stream of particles, known as photons, rather than just a wave. This is evident in the fact that the energy of the ejected electrons is directly proportional to the frequency of the incident light, rather than its intensity.

3. What is the work function in the photoelectric effect?

The work function is the minimum amount of energy needed to remove an electron from a metal surface. It varies depending on the type of material and is a crucial factor in determining the maximum kinetic energy of the ejected electrons in the photoelectric effect.

4. How does the photoelectric effect relate to the wave-particle duality of light?

The photoelectric effect is an example of the wave-particle duality of light, which states that light can behave as both a wave and a particle. In the photoelectric effect, light is considered to be made up of particles, yet it still exhibits wave-like behavior, such as diffraction and interference.

5. What are some practical applications of the photoelectric effect?

The photoelectric effect has many practical applications, including solar panels, photodiodes and photomultiplier tubes, which are used in various electronic devices. It also plays a crucial role in the development of quantum physics and our understanding of the nature of light.

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