Short Questions: Fun with Magnets | NCERT Summary: UPSC PDF Download

Q1: How can magnets be used to separate junk in a junkyard?
Ans: Materials such as iron, nickel, and cobalt, are attracted to magnets. Therefore, materials made of such magnetic substances can be separated in a junkyard by attracting them to a strong magnet. Hence, cranes with larger magnetic capacity are used in junkyards for separation of junk.

Q2: How can a compass be used to find directions?
Ans: A freely hanging magnet will always fall to the ground in a north-south orientation. A compass is made out of a magnetised needle that may freely rotate. The compass needle will always point north-south when it comes to rest. The needle will always point in the same direction. A compass can thus be used to determine north and south.

Q3: How can you make a compass in a cup?
Ans: Stepwise process of making a compass with a needle in a cup is as follows.

• Fill the cup with water so that it is almost full.
• Penetrate a cork or a piece of foam with this magnetised needle. 
• This cork or foam is allowed to float in water as long as the magnetised needle does not come into contact with the water. 
• Turn the cork. The needle will align itself in a north-south orientation when the cork stops revolving and continues to float without rotating.

Q4: Differentiate between magnetic and non-magnetic material.
Ans: Difference between magnetic and non-magnetic materials is as follows:

Q5: Explain magnetisation.
Ans: Magnetisation is the process of creating an artificial magnet with the help of a magnet. Place a piece of iron bar on the table. Then move one of the magnet's poles carefully along the entire length of the iron bar. It's important not to lift the magnet halfway. During this process make sure to use the same pole of the magnet to slide along the iron bar in the same direction each time. This method is repeated 30-40 times until the iron rod becomes magnetised.