## Introduction

In this article, I will solve examples of how to calculate the kinetic energy of an ejected electron from the metal. The kinetic energy of an electron that escapes the surface of the metal does not rely on the incident light and it depends on the frequency.

The formula for calculating the kinetic energy K.E of an electron that ejects from the surface of the metal is

K.E = 1/2 mv^{2} = E -W

where K.E = Kinetic energy of the ejected electron

W = workfunction

E = Illuminating radiation

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## Examples of How to Calculate the Kinetic Energy of an Ejected Electron

Here are a few examples to help you understand how to calculate the kinetic energy of an ejected electron from the metal:

### Example

The work function of a metal is 4.65eV and the illumination of radiation on the metal is 6.86eV. What is the kinetic energy of the electrons that eject from the surface of the metal?

**Solution**

**Data:**

The work function of the metal, W = 4.65eV

Illuminated radiation, E = 6.86eV

eV = 1.6 x 10^{-19}J

The kinetic energy of the electron, K.E =?

We can now apply the formula for the kinetic energy of the electron, which is

K.E = 1/2 mv^{2} = E – W

and we can write it as

K.E = E – W = 6.86eV – 4.65eV = 2.21eV = 2.21 x 1.6 x 10^{-19} = 35.36 x 10^{-20}J

Therefore, the kinetic energy of the electron to escape from the surface of the metal is 35.36 x10^{-20} Joules

I hope you have now understood how to calculate the kinetic energy of an ejected electron from the metal. Comment on what you don’t understand so that we can help you with more resources.

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**Reference**