Photoelectric Effect - Maximum Wavelength

In summary, the photoelectric effect occurs when a metal surface at zero potential emits electrons when exposed to light of a certain wavelength, in this case 450nm but not 650nm. This is because the wavelength must be below a certain maximum value, equal to the speed of light divided by the threshold frequency. The threshold frequency is related to the threshold energy, which is a key concept in quantum mechanics.
  • #1
LotusTK
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Hi, I am currently revising photoelectric effect, and i have this question:

A metal surface at zero potential emits electrons from its surface if light of wavelength of 450 nm is directed at it but not if light of 650nm is used. Explain why photoelectric emission happens with light of wavelength 450nm but not with light of wavelength 650nm

All i know is that the wavelength must be below a certain maximum value equal to the speed of light divided by the threshold frequency.

I don't know why this is, can someone explain why? Thanks.
 
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  • #2

FAQ: Photoelectric Effect - Maximum Wavelength

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 was first observed by Heinrich Hertz in 1887 and was later explained by Albert Einstein in 1905, who received a Nobel Prize for his work on the effect.

2. What is the maximum wavelength in the photoelectric effect?

The maximum wavelength in the photoelectric effect is the longest wavelength of light that can cause the emission of electrons from a material. This wavelength, also known as the threshold wavelength, is determined by the material's work function, which is the minimum amount of energy required to release an electron from the material's surface.

3. How does the intensity of light affect the maximum wavelength in the photoelectric effect?

The intensity of light does not affect the maximum wavelength in the photoelectric effect. The maximum wavelength is solely determined by the material's work function and is not affected by the intensity of light. However, the intensity of light does affect the number of electrons emitted from the material.

4. What is the relationship between the frequency of light and the maximum wavelength in the photoelectric effect?

The frequency of light and the maximum wavelength in the photoelectric effect are inversely proportional. This means that as the frequency of light increases, the maximum wavelength decreases. This relationship is described by the equation λmax = hc/Φ, where h is Planck's constant, c is the speed of light, and Φ is the material's work function.

5. How does the photoelectric effect support the wave-particle duality of light?

The photoelectric effect supports the wave-particle duality of light, which states that light has properties of both a wave and a particle. This is because the photoelectric effect can only be explained by considering light as a particle, known as a photon, that transfers its energy to electrons in the material, causing them to be emitted. However, the properties of light, such as diffraction and interference, can only be explained by considering it as a wave.

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