(a) Draw magnetic field lines around a current-carrying straight conductor.
(b) A compass needle is placed near a current-carrying straight conductor. State your observation for the following cases and give reasons for the same in each case :
(i) Magnitude of electric current is increased.
(ii) The compass needle is displaced away from the conductor.

Explanation

(a) See

(b) (i) On increasing the electric current strength of magnetic field increases and hence deflection of compass needle increases.
(ii) If the compass needle is displaced away from the current-carrying conductor, the magnitude of deflection decreases on account of decrease in strength of magnetic field.