Question

When the face of a coil towards an observer seems to carry current in .............. direction, north polarity is induced on that face.

• A. electromagnet
• B. right angles
• C. permanent
• D. anticlockwise

Answer 1

The correct option is D anticlockwise

When the face of a coil towards an observer seems to carry current in anticlockwise direction, north polarity is induced on that face.
The current flowing through the two parallel conductors of the loop are in opposite directions as the current through the loop exits the left hand side and returns on the right hand side. This results in the magnetic field around each conductor inside the loop being in the same direction to each other. The resulting lines of force generated by the current flowing through the loop oppose each other in the space between the two conductors where the two like poles meet thereby deforming the lines of force around each conductor as shown.
However, the distortion of the magnetic flux in between the two conductors results in an intensity of the magnetic field at the middle junction were the lines of force become closer together. The resulting interaction between the two like fields produces a mechanical force between the two conductors as they try to repel away from each other producing motion. However, as the conductors cannot move, the two magnetic fields therefore help each other by generating a north and a south pole along this line of interaction where the face of the coil has north polarity. This results in the magnetic field being strongest in the middle between the two conductors. The intensity of the magnetic field around the conductor is proportional to the distance from the conductor and by the amount of current flowing through it.