Space between two concentric conducting spheres of radii a and b (b > a) is filled with a medium of resistivity $$\rho $$. The resistance between the two spheres will be :

A moving coil galvanometer allows a full scale current of 10^–4 A. A series resistance of 2 M$$\Omega $$ is required to convert the above galvanometer into a voltmeter of range 0-5 V. Therefore the value of shunt resistance required to convert the above galvanometer into an ammeter of range 0.10 mA is :

A current of 5 A passes through a copper conductor (resistivity = 1.7 × 10^–8 $$\Omega $$m) of radius of cross-section 5 mm. Find the mobility of the charges if their drift velocity is 1.1 × 10^–3 m/s.

In the given circuit, an ideal voltmeter connected across the 10$$\Omega $$ resistance reads 2V. The internal resistance r, of each cell is: