•State and prove **Hall Effect**?

* Statement*:

When the magnetic field is applied perpendicular to the current carrying conductor then voltage is developed across the conductor.This voltage is known as **hall voltage** and the phenomena of production of ** hall voltage** is called

**hall effect**.

Consider a copper slab of width ‘d’ and thickness ‘t’ having and ‘n’ number of electrons per unit volume of slab. the area of slab is

**A= d*t** ……..1)

Let a current ‘I’ is applied from the face UPSC and a magnetic field ‘B’ is applied from the base PQRS then magnetic Lorentz forces acting on electron upward. so, upper facebecomes negatively charge whereas lower face becomes a positively charge. Due to the positive and negative charge ,an electric field is developed which opposees The Flow of electron. A voltage is developed when the electric force is balanced by the magnetic force. This voltage is known as **Hall Voltage and denoted by VH.**

**Now, Electric force = magnetic force**

**eE = BeVsin90°**

**eE = BeV**

**V = E/B** …….2)

Now, Current ‘I’ in a conductor is,

**I = venA** [Drift velocity]

**V = I/neA** ………3)

From equation 1 and 2, we get

** I/neA = E/B**

or, **BI/neA = E **

or, **BI/neA = V/d**

so*, V = BI/net*

This is required expression of **hall voltage .**

**Application of Hall Effect:**

1.It is to find no. of charge per. unit volume. [current density]

2. It is used to find magnetic flux density(B).

3.This effect is widly used in many devices as Hall senser.

4.It is used to the find sign of charge carrier.

*Question*

1)5)State and prove Joule’s laws of heating.

2)What do you meant by Shunt? Describe its use in converting a Galvanometer into Ammeter.