# Question about the photoelectric effect

• Dima Petrukhin
In summary, the conversation discusses the efficiency of a photodiode and the factors that can affect it, such as the work function and the energy of the incoming photons. It is also mentioned that the photoelectric effect is not described by the equation hf=work function+KEmax and that a single photon can be absorbed by the material without causing emission. The concept of quantum efficiency is also brought up in relation to this topic.
Dima Petrukhin
1. The question asks why the photodiode is less than 100% efficient.2. hf=work function+KEmax

3.- I reckon this is as some light will not cause e to be emitted if the wavelength of the light is less the needed.
-Or some photons will not hit any electron.

Is this correct?
Thinking about this question got me wondering if the work function may vary in a metal depending on how 'deep' the electron is in the metal?

And is it possible for a single photon to go through the metal without hitting an electron and not causing emission?

Thanks

I should say how close the electrons are to +ve metal ions

You say "photodiode" but you are describing the photoelectric effect. In a photodiode incoming photons create electron-hole pairs which are then detected as a current. This is not described by the equation hf=work function+KEmax.
Dima Petrukhin said:
And is it possible for a single photon to go through the metal without hitting an electron and not causing emission?
A single photon that does not cause emission does not have to go "through" the material. The photon's energy may be absorbed by the lattice and be dissipated as heat. Read about quantum efficiency here https://en.wikipedia.org/wiki/Quantum_efficiency.

## 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 or other electromagnetic radiation. This effect was first observed and studied by Albert Einstein in 1905.

## 2. How does the photoelectric effect work?

The photoelectric effect occurs when photons (packets of light energy) strike the surface of a material and transfer their energy to electrons. If the energy of the photon is greater than the material's work function (the minimum energy required to remove an electron from the material), then the electron will be emitted from the material.

## 3. What is the significance of the photoelectric effect?

The photoelectric effect provided evidence for the particle nature of light and helped to establish the field of quantum mechanics. It also has practical applications, such as in photovoltaic cells used in solar panels.

## 4. What factors affect the photoelectric effect?

The intensity and frequency of the incident light, as well as the properties of the material (such as its work function and electron density), can affect the photoelectric effect. Additionally, the presence of an external electric field can also influence the rate at which electrons are emitted.

## 5. How is the photoelectric effect related to the photoelectric equation?

The photoelectric equation, also known as the Einstein equation, describes the relationship between the energy of a photon, the work function of a material, and the maximum kinetic energy of the emitted electron. It is used to calculate various parameters of the photoelectric effect and is an essential element of understanding this phenomenon.

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