question_answer

A straight conductor carries a current vertically upwards. Points P and Q respectively lie to the east and west of the conductor at the same distance as shown below. How is P related to Q?

A) P has more magnitude than Q.

B) Q has more magnitude than P.

C) P and Q have the same magnitude.

D) P and Q may have the same or more magnitude.

Correct Answer: C

Solution :

As shown in the above figure, at point P in the magnetic field (b) (situated east of the wire), the field of the current-carrying wire will be directed north while at point Q is (situated west of the wire), it will be directed south but since radius (d) is the same, both will have the same magnitude \[B={{\mu }_{0}}{i}/{2}\;\pi r\].