Page 201 - NCERT Science Class 10 English Medium

12.1
12.1 MAGNETIC FIELD AND FIELD LINES
12.1 MAGNETIC FIELD AND FIELD LINESMAGNETIC FIELD AND FIELD LINES
MAGNETIC FIELD AND FIELD LINES
12.1
12.1 MAGNETIC FIELD AND FIELD LINES
We are familiar with the fact that a compass needle gets deflected when
brought near a bar magnet. A compass needle is, in fact, a small bar
magnet. The ends of the compass needle point approximately towards
north and south directions. The end pointing towards north is called north
seeking or north pole. The other end that points towards south is called
south seeking or south pole. Through various activities we have observed
that like poles repel, while unlike poles of magnets attract each other.

Q U E S T I O N

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

Activity
Activity 12.212.2
Activity 12.2
Activity 12.2
Activity 12.2
n Fix a sheet of white paper on a drawing
board using some adhesive material.
n Place a bar magnet in the centre of it.
n Sprinkle some iron filings uniformly
around the bar magnet (Fig. 12.2). A
salt-sprinkler may be used for this
purpose.
n Now tap the board gently.
Figure 12.212.2
Figure
Figure 12.2
Figure 12.2
n What do you observe? Figure 12.2
Iron filings near the bar magnet align
themselves along the field lines.
The iron filings arrange themselves in a pattern as shown
Fig. 12.2. Why do the iron filings arrange in such a pattern? What does
this pattern demonstrate? The magnet exerts its influence in the region
surrounding it. Therefore the iron filings experience a force. The force
thus exerted makes iron filings to arrange in a pattern. The region
surrounding a magnet, in which the force of the magnet can be detected,
is said to have a magnetic field. The lines along which the iron filings
align themselves represent magnetic field lines.
Are there other ways of obtaining magnetic field lines around a bar
magnet? Yes, you can yourself draw the field lines of a bar magnet.

12.3
Activity 12.3
Activity
Activity 12.312.3
Activity
Activity 12.3
n Take a small compass and a bar magnet.
n Place the magnet on a sheet of white paper fixed on a drawing
board, using some adhesive material.
n Mark the boundary of the magnet.
n Place the compass near the north pole of the magnet. How does
it behave? The south pole of the needle points towards the north
pole of the magnet. The north pole of the compass is directed
away from the north pole of the magnet.

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