question_answer 48)

  A constant current flows in a horizontal wire in the plane of the paper from east to west as shown in figure. The direction of magnetic field at appoint will be north to south. (a) Directly above the wire (b) Directly below the wire (c) At a point located in the plane of the paper on the north side of the wire (d) At a point located in the plane of the paper on the south side of the wire

Answer:

                  (b) According to right hand thumb rule, when conductor is held in right hand, keeping thumb from east to west as shown in the figure, the curve of the finger will be from north to south at a point lying directly below the wire.