Which sources produce alternating current?

In the activity,how do we think the displacement of rod $AB$ will be affected if:
$(i)$ current in rod $AB$ is increased;
$(ii)$ a stronger horse-shoe magnet is used; and
$(iii)$ length of the rod $AB$ is increased?

State whether the following statements are true or false.
$(a)$ The magnetic field at the centre of a long circular coil carrying current consists of parallel straight lines.
$(b)$ $A$ wire with green insulation is usually the live wire of an electric supply.

Which of the following properties of a proton can change while it moves freely in a magnetic field?

At the time of a short circuit,the current in the circuit:

$A$ coil of insulated copper wire is connected to a galvanometer. What will happen if a bar magnet is held stationary inside the coil?