Two wires '$$\mathrm{A}$$' and '$$\mathrm{B}$$' of equal length are connected in left and right gap respectively of meter bridge, null point is obtained at $$40 \mathrm{~cm}$$, from the left end. Diameters of the wires '$$A$$' and '$$B$$' are in the ratio $$3: 1$$ respectively, the ratio of specific resistance of 'A' to that of 'B' is

A galvanometer has resistance '$$\mathrm{G}$$' $$\Omega$$ and '$$\mathrm{I}_{\mathrm{g}}$$' is current flowing through it which produces full scale deflection. '$$\mathrm{S}_1$$' is the value of shunt which converts it into an ammeter of range 0 to '$$3 \mathrm{I}$$' and '$$\mathrm{S}_2$$' is the shunt value which converts it into an ammeter of range 0 to '$$4 \mathrm{I}$$', the ratio $$\mathrm{S}_2: \mathrm{S}_1$$ is

In potentiometer experiment, null point is obtained at a particular point for a cell on potentiometer wire '$$\mathrm{x}$$' cm long. If length of potentiometer wire is increased by few centimeter without changing the cell, the balancing length will [Driving source is not changed]

A galvanometer of resistance $$50 \Omega$$ is converted to an ammeter. After shunting, the effective resistance of ammeter is $$2.5 \Omega$$. The value of shunt is