R P Goyal and S P Tripathi Solutions for Chapter: Current Electricity, Exercise 1: EXERCISE-8(A)

Explain the analogy between the flow of charge (or current) in a conductor under a potential difference with the free fall of a body under gravity.

Name the particles which are responsible for the flow of current in a metal. Explain the flow of current in a metal on the basis of movement of the particles named by you.

What is the necessary condition for a conductor to obey Ohm's law ?

Define the term resistivity and state its S.I. unit.

 Name two factors on which the resistivity of a wire depends?

Two wires $A$and $B$ are made of copper. The wire $A$ is long and thin while the wire $B$ is short and thick. Which will have more resistivity ?

Give two differences between resistance and resistivity of a wire.

Two wires of the same material and same length have radii $1 \mathrm{mm}$ and $2 \mathrm{mm}$ respectively. Compare their resistivities.