Magnetic Effects of Electric Current

Class 10 NCERT Science

NCERT

1   Why does a compass needle get deflected when brought near a bar magnet?

Solution :

A compass needle is a small bar magnet. When it is brought near a bar magnet, its magnetic field lines interact with that of the bar magnet. Hence, a compass needle shows a deflection when brought near the bar magnet.

2   Draw magnetic field lines around a bar magnet.

Solution :

Magnetic field lines of a bar magnet emerge from the north pole and terminate at the south pole. Inside the magnet, the field lines emerge from the south pole and terminate at the north pole, as shown in the given figure.

3   List the properties of magnetic lines of force.

Solution :

The properties of magnetic lines of force are as follows.$\\$ (a) Magnetic field lines emerge from the north pole.$\\$ (b) They merge at the south pole.$\\$ (c) The direction of field lines inside the magnet is from the south pole to the north pole.$\\$ (d) Magnetic lines do not intersect with each other.

4   Why don’t two magnetic lines of force intersect each other?

Solution :

If two field lines of a magnet intersect, then at the point of intersection, the compass needle points in two different directions. This is not possible. Hence, two field lines do not intersect each other.

5   Consider a circular loop of wire lying in the plane of the table. Let the current pass through the loop clockwise. Apply the right-hand rule to find out the direction of the magnetic field inside and outside the loop.

Solution :

Inside the loop = Pierce inside the table$\\$ Outside the loop = Appear to emerge out from the table$\\$ For downward direction of current flowing in the circular loop, the direction of magnetic field lines will be as if they are emerging from the table outside the loop and merging in the table inside the loop. Similarly, for upward direction of current flowing in the circular loop, the direction of magnetic field lines will be as if they are emerging from the table outside the loop and merging in the table inside the loop, as shown in the given figure.