Electric motor converts mechanical energy into electrical energy.

$(a)$ What is an electromagnet? What does it consist of?
$(b)$ Name one material in each case which is used to make a: $(i)$ permanent magnet $(ii)$ temporary magnet.
$(c)$ Describe an activity to show how you can make an electromagnet in your school laboratory.

The diagram below shows a circuit containing a coil wound over a long and thin hollow cardboard tube. Copy the diagram and:
$(i)$ Show the polarity acquired by each face of the solenoid.
$(ii)$ Draw the magnetic field lines of force inside the coil and also show their direction.
$(iii)$ Mention two methods to increase the strength of the magnetic field inside the coil.

The magnetic field produced by a current-carrying solenoid depends directly upon the strength of the current.

When an electric current flows through a conducting wire,what is produced in the region around it?

$(a)$ $A$ coil of insulated copper wire is connected to a galvanometer. What will happen if a bar magnet is:
$(i)$ pushed into the coil with its north pole entering first?
$(ii)$ withdrawn from inside the coil?
$(iii)$ held stationary inside the coil?
$(b)$ Name the above phenomenon and mention the name of the scientist who discovered it. State the law that relates the direction of current in the coil with the direction of motion of the magnet.