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

Explanation

Current sensitivity of a galvanometer is defined as the deflection in galvanometer per unit current. Its SI unit is Radians/Ampere.
For balanced Wheatstone bridge, there will be no deflection in the galvanometer.
`(4)/(R_(1))=(6)/(9)" "R_(1)=(4 xx 9)/(6) = 6 Omega`.
For the equivalent circuit, when the Wheatstone. bridge is balanced, there will be no deflection in the galvanometer.
`(12)/(8)=(6)/(R_(2)) rArr R_(2)=(6 xx 8)/(12) = 4 Omega`
`(R_(1))/(R_(2))=(6)/(4)=(3)/(2) rArr 3 : 2`.