The potentiometer wire `AB` shown in figure is `40 cm` long. Where the free end of the galvanometer should be connected on `AB` so that the galvanometer may show zero deflection?

Explanation

Let the free end of galvanometer be connected on `AB` at distance `x` from `A`
`(8)/(12) = (AP)/(PB) = (x)/(40 - x)`
`(2)/(3) = (x)/(40 - x)`
`80 - 2x = 3 x rArr 5x = 80 rArr x = 16 cm`.