Solution

(a)Resistance is defined as ratio of potential difference applied across the ends of the conductor to the current flowing through it.
Resistivity is defined as the resistance of unit cube of that material.It depends upon the nature of the material and temperature of the material.
(b)

Solution

Solution

Focal length of objective lens=1/100 m=1 cm

Solution

Solution

Solution

(a)(i)Equipotential surfaces do not intersect each other as it gives two directions of the electric field at the intersecting point which is not possible.
(ii)Equipotential surfaces are closely spaced in the region of strong electric field and widely spaced in the region of weak electric field.
(b)Suppose the ring is placed with its plane perpendicular to the X-axis as shown in the figure. Consider small element dl of the ring.

Solution