Free vibrations are :

1. the vibrations under the influence of a periodic force.
2. the vibrations with larger amplitude.
3. the vibrations when the frequency continuously decreases.
4. the vibrations with a constant frequency and constant amplitude.

The graph plotted for potential difference (V) against current (I) for ohmic resistors is :

1. A curve passing through the origin.
2. A straight line not passing through origin.
3. A straight line passing through the origin.
4. A circle centred at the origin.

A main switch in the main distribution board is present in :

1. a live wire
2. a neutral wire
3. a live as well as neutral wire
4. an earth wire

A conductor AB is kept along north south direction of the earth above a magnetic needle as shown below. When the key K is closed then:

1. the needle will not show any deflection.
2. the needle will deflect towards east.
3. the needle will turn in the opposite direction i.e. towards south.
4. the needle will deflect towards west.