Question

Write the answers in your words.
(a) How is an electromagnet made?
(b) Write the properties of a magnet.
(c) What are the practical uses of a magnet?

Answer 1

(a) For the construction of an electromagnet, we require an iron nail, a long insulated copper wire, a battery and a switch.
The long insulated copper wire is first wound on the iron nail. Then the two free ends of the wire is connected to the battery and the switch as shown. Now, when the switch is turned on, current flows through the circuit. Due to this flow of current, the insulated copper wire and iron nail acts as an electromagnet. Now, if iron pins are brought close to this set-up, they stick to the iron nail.
As soon as the current stops flowing in the circuit, the iron nail loses magnetism and the pins fall off.


(b) Properties of a magnet are following:

• A magnet has two poles known as North-Pole and South-Pole.
• A magnet, when suspended freely, always rests in north-south direction.
• A magnet has an attractive properties i.e. it always attracts magnetic materials towards it.
• Like poles of magnets repel each other whereas unlike poles attract each other.
• The two poles of a magnet are inseparable. It means that when a magnet is cut into two parts, two independent magnets are formed.
• Magnetic force of a magnet is concentrated at its two poles.

(c) Magnets have very wide range of uses:

• Magnetic compass: With the help of a magnetic compass, you can know the directions at a particular place. The red end of the needle indicates the North direction.

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• Magnets in daily life: Magnets are used in refrigerator doors, as pin holders, in screwdrivers, etc.
• Magnet in junkyard: In the junkyard, you will see that a large magnet is attached at the bottom of the arm of a crane. The arm moves over a heap of junk and the magnet collects objects made of iron. The magnet used in a junkyard crane is not a natural or a permanent magnet. It is a temporary magnet, which is called an electromagnet.
• Magnet in electrical appliances: Magnets are also used in many electrical appliances such as electric bells, telephone, telegraph, radio, loudspeaker, fans, electrical motors, electric generator, etc.
• Magnet for security: While going to some important places like temples, buildings, airport etc. you will see equipments for inspection of people entering these places. These equipments uses magnets and are known as Metal detectors. These metal detectors are also used in food-processing industry to detect any unwanted iron/steel objects mixed unknowingly in food stuff.