Earthing of electrical appliances is very important.

$A$ magnetic compass shows a deflection when placed near a current-carrying wire. How will the deflection of the compass be affected if the current in the wire is increased? Support your answer with a reason.

Who first observed that a current-carrying wire experiences a force when placed in a strong magnetic field?

In an electric motor,a loop with many turns is arranged on an axis. What is it called?

The magnetic field produced by a straight current-carrying conductor is in the form of concentric circles.

$(a)$ Explain any three properties of magnetic field lines.
$(b)$ Give two uses of magnetic compass.