All the resistance in the given Wheatstone bridge have different values and the current through the galvanometer is zero. The current through the galvanometer will still be zero if,

Options

A. the emf of the battery is doubled
B. all resistance are doubled
C. resistances `R_1 and R_2` are interchanged
D. the battery and the galvanometer are interchanged.

Answer

A, B, D

Explanation

a., b., d.
If `R_1//R_2 = R_3//R_4`, there will be no current through galvanometer
If emf of battery of double, there will not be any charge is
situation i.e., `(R_1//R_2 = R_3//R_4)`. Even if all the resistances
are doubled, the ratio remains same. If the positions of the
galvanometer and battery si interchanged, the ratio `R_1 //R_3 = R_2//R_4`
will remains same.