The magnetic field at the centre of a current carrying circular coil of area 'A' is 'B'. The magnetic moment of the coil is ( $$\mu_0=$$ permeability of free space)

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 hollow charged metal sphere has radius 'R'. If the potential difference between its surface and a point at a distance '5 R' from the centre is $$\mathrm{V}$$, then magnitude of electric field Intensity at a distance '5R' from the centre of sphere is