Question

Define work function. Write its unit.

Hint:

The work function is an important concept in the photoelectric effect and is specific to the material from which electrons are emitted.

Answer 1

Step 1: Definition of Work Function.
The work function (\( \phi \)) is the minimum energy required to remove an electron from the surface of a material (usually a metal) to a point where the electron is free from the material. This is the energy needed to overcome the attractive forces binding the electron to the material.
Step 2: Unit of Work Function.
The work function is measured in joules (J). Since energy is expressed in joules, the unit of the work function is also joules.
Final Answer:
The work function is the minimum energy required to free an electron from a material, and its unit is \( \boxed{\text{Joules (J)}} \).