In the straight wire A, current is flowing in the vertically downward direction whereas in wire B the current is flowing in the vertically upward direction. What is the direction of magnetic field:
(a) in wire A?
(b) in wire B?
Name the rule which you have used to get the answer.
(a) Clockwise would be the direction of magnetic field in wire A.
(b) the direction of the magnetic field in the wire B is anticlockwise.
Maxwell’s right hand thumb rule.