A …………… is either used to detect the presence of a weak current or to only know the direction of flow of current in a circuit.

1. ammeter
2. galvanometer
3. voltmeter
4. rheostat

Insulators have ……………electrons and conductors have …………… electrons.

1. no free, large number of free
2. large number of free, no free
3. no free, small number of free
4. small number of free, no free

The presence of …………… in the path makes a circuit incomplete and current does not flow.

1. conductor
2. ammeter
3. voltmeter
4. insulator

Select the best insulator among the following

1. Pure water
2. Human body
3. Aluminium
4. Mercury