Name any three factors on which the magnitude of the magnetic field due to a solenoid depends.

$A$ current $I$ passes through a circular loop $C$ and a solenoid $AB$ as shown below:
$(i)$ What is the polarity of: $(a)$ the face of the loop you are looking at? $(b)$ the end $B$ of the solenoid?
$(ii)$ What is the direction of the magnetic field at the centre of the loop?

What is a solenoid? Draw the magnetic field lines for a solenoid and a bar magnet. Compare the two and state one similarity.

In an electric circuit,a fuse is used because $......$

The diagram below shows a coil connected to a centre zero galvanometer $G$. The galvanometer shows a deflection to the right when the $N$ pole of a powerful magnet is moved to the right as shown.
$(i)$ Explain why the deflection occurs in the galvanometer.
$(ii)$ Does the direction of current in the coil appear clockwise or anticlockwise when viewed from end $A$?
$(iii)$ State the observation in $G$ when the coil is moved away from $N$.
$(iv)$ State the observation in $G$ when,both coil and the magnet,are moved to the right at the same speed.

Explain the phenomenon of electromagnetic induction. Describe an experiment to show that a current is set up in a closed loop when an external magnetic field passing through the loop increases or decreases.