To obtain maximum sensitivity and accuracy in a meter bridge, it is advised to obtain a null point at

Question

Question

Answer 1

CONCEPT:

Meter Bridge:

A meter bridge also called a slide wire bridge is an instrument that works on the principle of a Wheatstone bridge.
- A meter bridge is used in finding the unknown resistance of a conductor as that of in a Wheatstone bridge.
In a meter bridge, a wire having a length of a uniform cross-section of about 1m is used.
One known resistance and an unknown resistance are connected as shown in the figure.
The one part of the galvanometer is connected in between the known and unknown resistances, whereas the other part of the wire is used to find the null point where the galvanometer is not showing any deflection.
At this point, the bridge is said to be balanced.

F1 P.B 8.5.20 Pallavi D5

EXPLANATION:

To obtain maximum sensitivity and accuracy in a meter bridge, it is advised to obtain a null point at the middle of the wire.
- In the middle of the wire ratio arms are nearly equal in resistance.
Wheatstone bridge is most sensitive when the resistance of its four-arm is of the same order. Since the Meter bridge works on the principle of Wheatstone bridge, balance point or null point is obtained at the middle of the Meter bridge wire.
The end resistance of the copper strips also produces the least effect. Hence option 3) is correct.

Additional Information

Wheatstone bridge principle:

It states that if four resistances R1, R2, R3, and Rx are arranged in form of a bridge with a cell of EMF E connected between A and C and a galvanometer between B and D and on closing the key if the galvanometer shows no deflection, then the bridge is balanced.
In that case: $\frac{R_{1}}{R_{2}} = \frac{R_{3}}{R_{x}}$

F1 Prabhu Madhuri 05.05.2021 D16