Describe an activity to show that magnetic field is produced by an electric current flowing through a circular coil of wire.

A proton enters a magnetic field at right angles to it as shown in the figure. What is the direction of the force acting on the proton?

A charged particle enters at right angles into a uniform magnetic field as shown. What should be the nature of charge on the particle if it begins to move in a direction pointing vertically out of the page due to interaction with magnetic field.

State the direction of magnetic field in the following case.

(a) What are the factors on which the magnetic field produced by the current-carrying circular coil depends?
(b) What happens if the current through the coil is reversed?