Question

3. In Kelvin's method, the bridge will balance when galvanometer shows....
(a) zero deflection (b) null deflection (c) full deflection
Ans.:..​

Answer 1

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In Kelvin's method, the bridge will balance when galvanometer shows....

(a) zero deflection (b) null deflection (c) full deflection

❦$\small \blue {\sf{Answer }}$

• Kelvins method to determine the resistance of the galvanometer by using a meter bridge:

A galvanometer whose resistance 'G is to be determined is connected in one gap (left gap) of a Wheatstones meter bridge and a resistance box is connected in the other gap (right gap).

1. G : Galvanometer
2. R : Resistance from the resistance box
3. AC : Metal wire one meter long
4. Rh : Rheostat
5. E : Cell.
6. K :Plug key
7. K : Jockey

A cell of emf 'E', key K and rheostat Rh are connected in series with the bridge wire AC. The junction B of the galvanometer and the resistance box is connected to the jockey which can slide along wire AC.

A suitable resistance K is taken in the resistance box and a current J is sent round the circuit. Without touching the jockey to any point of AC, note the deflection in the galvanometer.