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 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 a meter bridge experiment, the circuit diagram and the corresponding observation table are shown in figure

SI. No.	R($$\Omega $$)	l(cm)
1.	1000	60
2.	100	13
3.	10	1.5
4.	1	1.0

Which of the readings is inconsistent?

In an experiment, the resistance of a material is plotted as a function of temperature (in some range). As shown in the figure, it is a straight line. One may conclude that :