Name: Applications of Potentiometer
Uploaded: 2019-07-19
Duration: 4 min 30 s
Description: Since potentiometers are very versatile and handy to use, it is vital to understand their working principle and applications fully. In this video, learn abou...

Question

Draw a neat circuit diagram of the Wheatstone bridge and mention the importance of such a bridge. Also, obtain its condition of balance.

Accepted Answer

Wheatstone bridge is shown in the figure with resistances $P, Q, R and S .$

Importance of Wheatstone bridge

The Wheatstone bridge is used for the precise measurement of low resistance.

Wheatstone's bridge along with operational amplifier is used to measure physical parameters such as temperature, light, and strain.

Quantities such as impedance, inductance, and capacitance can be measured using variations on the Wheatstone bridge.

The Wheatstone bridge is said to be balance if no current flows through the galvanometer $G$ .

Wheatstone bridge (balanced) - Let $i$ be the current from battery $E$ . At point $A$ , current $i_{1}$ flows through resistance $P$ and current $i - i_{1}$ flows through $R$ . In balanced state , no current flows through $B D$ , hence point $B$ and $D$ are at same potential. Therefore, current $i_{1}$ flows through resistance $Q$ also and current $i - i_{1}$ flows through $S$ .

Applying Kirchhoff's loop rule in closed mesh $A B D A$ ,

$i_{1} P - (i - i_{1}) R = 0$

$i_{1} P = (i - i_{1} ) R . . . . . . . . . . . . . . . . . . . 1$

In closed mesh $B C D B$ ,

$i_{1} Q - (i - i_{1} ) S = 0$

$\Rightarrow i_{1} Q = (i - i_{1} ) S$

Dividing both equations, we get

$\frac{P}{Q} = \frac{R}{S}$

This is the condition for balance in a Wheatstone bridge.

Draw a neat circuit diagram of the Wheatstone bridge and mention the importance of such a bridge. Also, obtain its condition of balance.

Important Questions on Direct Current Circuits

Learn and Prepare for any exam you want !