ABSTRACT

A compass needle itself consists of a north and south pole, it being a small magnet free to rotate on a spindle. A compass needle placed in the vicinity of the coil would tend to align itself with the field surrounding the coil. Now, outside the coil, the alignment results in the familiar observation that like poles repel and unlike poles attract. Inside the coil, the compass needle is still aligned with the field but we can no longer say that like poles repel and unlike poles attract. Rather, it is more scientifically appropriate to say that when two magnetic fields interact, they tend to align themselves. This

South to indicate the direction of the external field. These labels have come about since it is the direction in which the solenoid would tend to align itself with the magnetic field of the earth if it were free to move.