Question

Why does a magnetic compass needle pointing North and South in the absence of a nearby magnet get deflected when a bar magnet or a current-carrying loop is brought near it. Describe some salient features of the magnetic lines of field concept.

Answer 1

The reason why the magnetic compass needle gets deflected:

1. The conductor acts like a bar magnet when electric current flows through it, creating an induced EMF that causes magnetic lines of force to form all around it.
2. The magnetic field produced by the current-carrying conductor and the earth's magnetic field is superimposed.
3. Therefore, when a magnetic compass that is pointing north-south according to the earth's magnetic field exhibits deflection in relation to the strength of the magnetic field.
4. In simple words, the magnetic fields of the compass needle and the bar magnet (or current-carrying loop) interact, causing the deflection to happen.

Salient features of the magnetic lines of field:

1. Magnetic field lines go from the north pole to the south pole in a clockwise direction.
2. Magnetic field lines have a concentric pattern all the time.
3. Lines of the magnetic field do not intersect one another.
4. The magnetic field is greater when the field lines are closer together, and vice versa.
5. Near the poles, magnetic field lines are closer together, indicating a stronger magnetic field.