Page 48 - Innovator's Science-8

Science • Tightly wind around 50 turns of the
Bytes
insulated wire on the cylinder to form a
cylindrical coil as shown. Secure the wire
(b)
Testimony with an adhesive tape. (a)
• Electromagnets are (a) A coil of insulted wire
used in everything • Place the compasses near the two ends of
from cket machines the cylindrical coil.
(c)
and telephones to • Connect the two ends of the coil with the terminals of the
loudspeakers.
cell as shown and observe the magne c compasses. Do
• Every electric current
creates its own you find any deflec on in the needles of the compasses? (d)
magne c field. • Disconnect the wire from the cell. Do the needles of the
compasses come back to their original posi ons?
• Insert an iron nail in the paper cylinder and repeat the
steps.
(e)
• Is there any difference in the deflec on of the compass (b) Coil and magnetic compasses;
(c) Coil connected to a cell;
needles? (d) Coil with iron nail inserted;
(e) Coil with iron nail and clips
• Place some iron paper clips near the two ends of the nail.
Are the clips a racted to the ends of the nail?
Observa on: It is observed that when electric current passes through a coil of wire,
the coil acts like a magnet and can move the needle of a magne c compass. If an iron
nail is placed inside the coil, the magnet becomes stronger and can a ract iron
objects like paper clips. When the electric current is turned off, the magne c effect

When electricity flows through a coil of wire, it turns into a magnet with
two ends, just like a bar magnet. In this activity, we use the electromagnet
you made and a magnetic compass. The ends of the coil are labelled A and

B. When you place the compass near end A and connect the coil to a
battery, the compass needle moves. By watching which end of the compass
needle points toward end A, you can find out which magnetic pole end A

has. This shows that an electromagnet has a North and South Pole like a
regular magnet.

(a) (b)
Compass needle near (a) End A; (b) End B of an electromagnet

A magnet that is freely hung always points in the north–south direction
because the Earth itself acts like a huge magnet. This happens because,
deep inside the Earth, the movement of molten (liquid) iron in the core

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Science-8