Exploring Magnets

D. Tick (√ ) the odd-one out giving reason.

1. Allpins, Paper, Pencil, Eraser, Compact disc
Ans. Allpins – are made of metal and are attracted by a magnet.

2. Bar magnet, Sawdust, Card board sheet
Ans. Sawdust – Bar Magnet and Cardboard Sheet are commonly used together to demonstrate magnetic field patterns (cardboard is placed over the magnet).

3. Magnesia, Magnes, Ironsmith, Greece
Ans. Ironsmith – A profession; others are related to the discovery of  agnets.

4. Iron, Cobalt, Silver, Nickel

Ans. Silver – Non-magnetic; others are magnetic.

II.LOGIC BASED QUESTIONS

Short and Long Answer

1.  You are provided with three identical metal bars, out of which two are magnets while one is a piece of iron. Suggest a way to identify the two magnets out of these three without the help of any other material.
Ans. Bring one bar close to the others. If repulsion occurs, both bars involved are magnets. Repulsion is the sure test of magnetism.

2. Sarthak suspended a bar magnet over a heap of iron alpins. What would be his most likely observation from among the given options ? Also, give reason for your analysis.
(a) NS
(b) NS
(c) NS
(d) NS
Ans. Most iron alpins will stick near the ends (poles) of the magnet because magnetic strength is maximum at the poles.
Correct option: (c)

3. What happens to a magnet when it is beaten into two pieces ?
Ans. Each piece becomes a complete magnet with two poles.

4. Can the north pole and south pole of a magnet be separated ?

Ans. No, magnetic poles always occur in pairs and cannot be separated.

III. HIGHER ORDER THINKING SKILLS

1. Why magnets should be kept away from electronic devices ?

Ans. Magnets can damage electronic circuits, data storage devices, and screens by disturbing their magnetic fields.

2. Why is the compass needle enclosed in a glass cover ?

Ans. The glass cover protects the needle from air, dust, and damage, while still allowing the  magnetic field to pass through.