Question

If the key in the given arrangement is taken out (the circuit is made open) and magnetic field lines are drawn over the horizontal plane ABCD, the lines are ____________.

Options

• concentric circles

• elliptical in shape

• straight lines parallel to each other

• concentric circles near the point O but of elliptical shapes as we go away from it

Answer 1

If the key in the given arrangement is taken out (the circuit is made open) and magnetic field lines are drawn over the horizontal plane ABCD, the lines are concentric circles.

Explanation:

When open magnetic field lines are drawn over the horizontal plane ABCD, the magnetic field lines form concentric circles, with the center at the conductor's axis.

This is because there will be no current flow, and so no magnetic field is generated by the conductor.

As a result, only the Earth's magnetic field will be present at point O, causing the magnetic field lines to form concentric rings.