# Photoelectric effect and cutoff frequency

• lha08
In summary: What could it represent?In summary, the conversation discusses how to find the cutoff frequency when given a graph of Stopping Potential versus Frequency of light and the values for Wavelength and Stopping Potential. The conversation suggests using the equation for the photoelectric effect and rearranging it to make V the subject of the equation. From there, the gradient of the graph represents the work function and the intercepts on the y and x-axis represent the work function and the cutoff frequency, respectively. The conversation also discusses the units for these values and their significance in finding the cutoff frequency.
lha08

## Homework Statement

I was just wondering that when I have a graph of the Stopping Potential versus Frequency of the light. How can I find the value for the cutoff frequency?
Wavelength Vo
160 nm 2.99 V
53 nm 19.18 V
80 nm 11.00 V
160 nm 2.93 V
187 nm 1.92 V

## The Attempt at a Solution

What attempt have you made?

Write down the equation for the photoelectric effect and then use the fact that the stopping potential is the work done in stopping the electrons from having any kinetic energy.

What attempt have you made?

well i found the theoretical value of the slope: 4.14125 X 10^-15 Js/C and the actual value of the slope: 3.9512 X 10^15 J s/C but don't know how to use them to find the answer

As rockfreak advised write down the equation.Next rearrange it to make V the subject of the equation and then compare what you have to the equation of a straight line.By comparison you should be able to identify what the gradient of the graph represent and what the intercepts on the y and the x-axis represent.

Last edited:
As rockfreak advised write down the equation.Next rearrange it to make V the subject of the equation and then compare what you have to the equation of a straight line.By comparison you should be able to identify what the gradient of the graph represent and what the intercepts on the y and the x-axis represent.

does the y intercept of the graph represent the work function?

Did you plot V on the y axis?If so the intercept has the units of volts ie joules per coulomb.The work function has the units of Joules so what could the intercept represent?Also, look at the intercept on the x axis.

## 1. What is the photoelectric effect?

The photoelectric effect is the phenomenon where electrons are emitted from a metal surface when it is exposed to light of a certain frequency. This effect was first discovered by Albert Einstein in 1905 and is a fundamental principle in quantum mechanics.

## 2. How does the photoelectric effect work?

When light of a certain frequency, known as the threshold frequency, hits a metal surface, it transfers its energy to the electrons in the metal. If the energy of the light is greater than the work function of the metal, the electrons will have enough energy to overcome the attractive forces of the metal and be emitted as photoelectrons.

## 3. What is the relationship between the frequency of light and the kinetic energy of the emitted electrons?

According to the photoelectric effect equation, the kinetic energy of the emitted electrons is directly proportional to the frequency of the incident light. This means that as the frequency of the light increases, the kinetic energy of the emitted electrons also increases.

## 4. What is the cutoff frequency in the photoelectric effect?

The cutoff frequency is the minimum frequency of light required to cause the photoelectric effect. If the frequency of the incident light is below the cutoff frequency, no electrons will be emitted regardless of the intensity of the light. The cutoff frequency is determined by the work function of the metal.

## 5. How is the photoelectric effect used in technology?

The photoelectric effect has many practical applications, such as in solar cells, photodiodes, and photomultiplier tubes. These technologies utilize the photoelectric effect to convert light energy into electrical energy, making them crucial in fields such as renewable energy, telecommunications, and medical imaging.

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