In the shows arrangement of a meter bridge, if `AC` corresponding to null deflection of galvanometer is x, what would be its value if the radius of the wire `AB` is doubled?

Options

A. `x`
B. `x//4`
C. `4x`
D. `2x`

Answer

A

Explanation

At null point, `R_(1)//R_(2) = R_(3)//R_(4) = x//(100 - x)`. If radius of the wire is doubled, then the resistance of `AC` will change and the resistance of `CB` will also change. But since `R_(1)//R_(2)` does not change, so `R_(3)//R_(4)` should also not change at null point. Therefore, point `C` does not change.