Four metal rods are placed, in turn, inside a coil of copper wire.

The table below gives the results of the experiment. Which rod would be the most suitable to use for the case of a coil in a circuit breaker?

Meta rod	Number of paper clips picket up when there is current in the coil	Number of paper clips still attracted when the current is switched off
(a)	$1$	$0$
(b)	$20$	$2$
(c)	$35$	$0$
(d)	$35$	$30$

Describe the magnetic field produced by a solenoid carrying current.

Kunal draws magnetic field lines close to the axis of a current carrying circular loop. As he moves away, towards the centre of the circular loop, he observes that the lines keep on diverging. How will you explain his observation?

Electricity and magnetism are linked to each other.
Why does a current carrying solenoid when suspended freely rest along a north-south direction?

Observe the given figure of Fleming' s Right Hand Rule and write the labels of A and B correctly.

The diagram below shows a magnetic needle kept just below the conductor AB which is kept in the North-South direction.

i) In which direction will the needle deflect when the key is closed?

ii) Why is the deflection produced?

iii) What will be the change in the deflection if the magnetic needle is taken just above the conductor AB?

iv) Name one device which works on this principle.

The diagram shows a current carrying wire passing through the centre of a square card board. The magnetic field at points $A$, $B$  and $C$ is:

The magnetic field around a current carrying conductor AB is given in the figure. Based on Maxwell's right-hand screw rule, find the direction of the current through the conductor. 

What is a solenoid? Can you determine the North and South poles of a current-carrying solenoid with the help of a bar magnet? Explain.