Question

A circular loop is kept in that vertical plane which contains the north-south direction. It carries a current that is towards north at the topmost point. Let A be a point on the axis of the circle to the east of it and B be a point on this axis to the west of it. The magnetic field due to the loop:
(A) is towards east at A and towards west at B
(B) is towards west at A and towards east at B
(C) is towards east at both A & B
(D) is towards west at both A & B

Answer 1

Hint: Loop is in the vertical plane. Current is towards the north at the top most point. From Maxwell equation we know a current carrying loop produces a magnetic field of its own. Also, the direction of the field can be found using a number of given laws.

Complete step by step answer:
In this problem first of all we need to draw the diagram to have a better clarity about the problem given.

North south direction means the loop is lying in the vertical plane. By using the right hand thumb rule, the direction of the magnetic field can be found both at Point A & Point B.
Upon its application we find that at both the points the direction of the magnetic field is towards the west.

So, the correct answer is “Option D”.

Note:
Right hand thumb rule has two components- the figures and the thumb. Fingers are curled. If fingers represent the direction of current then the thumb points in the direction of the magnetic field and if the thumb represents the direction of the magnetic field then the fingers represent the direction of current. We can use them interchangeably.