Question

When a resistance of 20 ohm
connected in parallel
with a galvanometer then its deflection reduces
from 50 divisions to 10 divisions, the resistance of
galvanometer is
(1) 80
(2) 100
(3) 400
(4) 500​

Answer 1

Answer:

Option 1 i.e 80 ohm

Explanation:

Let the value of current passing through galvanometer per division is i amp

Current through 50 divisions of ammeter  will be 50i

When a resistance of 20 ohm is connected in parallel, cuurent through galvanometer is 10i

20 = ( 10i / 50i – 10i) x Gr

Gr = (50i – 10i / 10i) x (20)

Gr = 80 ohm

Hence galvanometer resistance is 80 ohm