Question

The galvanometer, in each of the two given circuits does not show any deflection. Find the ratio of the resistors `R_(1)` and `R_(2)` used in these two circuits.

Answer 1

In circuit 1, the Wheatstone bridge is in balanced state so,
`4/R_(1) = 6/9`
or `R_(1) = (4xx9)/6 = 6 Omega`
In circuit 2, the positions of galvanometer and battery are interchanged but the galvanometer shows no defelction, means the bridge is in balanced state, so
`6/12 = R_(2)/8 or R_(2) = (6xx8)/12 = 4 Omega`
`R_(1)/R_(2) = 6/4 = 3/2` or `R_(1) : R_(2) = 3:2`