Fill in the following blank with a suitable word :

Ohm's law states a relation between potential difference and ........................

A resistance of 20 ohms has a current of 2 amperes flowing in it. What potential difference is there between its ends?

A current of 5 amperes flows through a wire whose ends are at a potential difference of 3 volts. Calculate the resistance of the wire.

Distinguish between good conductors, resistors and insulators. Name two good conductors, two resistors and two insulators.

Classify the following into good conductors, resistors and insulators:

Rubber, Mercury, Nichrome, Polythene, Aluminium, Wood, Manganin, Bakelite, Iron, Paper, Thermocol, Metal coin