question_answer

An electric current passes through a straight wire. Magnetic compasses are placed at the points X and Y.

A) Their needles will not deflect.

B) Only one of the needles will deflect.

C) The needles will deflect in the same direction.

D) The needles will deflect in the opposite directions.

Correct Answer: D

Solution :

Current carrying wire produces magnetic field, but direction of magnetic field on the given points X and Y are different. This is found by right hand thumb rule. So magnetic compasses on X and Y experience magnetic force of same magnitude but in opposite directions. Hence, the needles will deflect in opposite directions.