22 October 2012

Class 6th Fun with magnet CBSE /NCERT Questions with answer

CBSE NCERT Class VI Science Lesson 13:Lesson 13: Fun with Magnets.
1. Who discover magnet?
Ans: A Greek shepherd named Magnes discovered magnets 4,000 years ago in Magnesia, Greece. The name magnetite has been derived from Magnesia or Magnes.
2. What is magnet?
Ans: Any material that attract iron object is called magnet. The two ends of a magnet are called its poles. The poles of a magnet are named as the North Pole and the South Pole. In order to identify the poles, the North Pole is usually painted in red colour. All magnets have two poles, and they are called dipoles.  Law of magnets :Unlike poles attract each other and like poles repel each other.
3. Why magnet called load stone?
Ans: Magnet in the form of a bar was used to find directions on the earth, and so it is called as a Lodestone.
4. What are magnetic material and Non-Magnetic Materials?
Ans: Materials that are attracted by a magnet are called magnetic materials. Objects made of materials such as iron, cobalt and nickel are magnetic objects. Examples of magnetic materials include iron nail, key, metal spade, needle and metal door handle.
Materials that are not attracted by magnets are called non-magnetic materials. Examples of non-magnetic materials include rubber, coins, feather and leather.
5. What are different types of magnets?
Ans: Bar magnets : In these magnets, the poles are located at the ends of the bar.
Cylindrical magnets:  In these magnets, the poles are located at the two circular ends of the cylinder.
Horseshoe magnets : In these magnets, the poles are located at the two free ends of the 'U' shape.
6. What is Compass?
Ans: A compass is an instrument that is used to find the directions. It has a thin magnetic needle supported from a pivot so that it can rotate freely. The needle is placed over a dial with the directions marked. The entire assembly is placed inside an airtight box.
7. How can you make artificial magnets?
Ans: A rectangular iron bar, an iron needle, a blade or an iron nail can be turned into a magnet by rubbing a bar magnet over like combing hair to make artificial magnets.
8. How do you protect magnets from losing their magnetic properties?
Ans: Precautions to protect magnets from losing their magnetic properties are:
(a) Never drop magnets from heights. (b) Never heat a magnet. (c) Do not hammer a magnet.
9. Write some use of magnet?
Ans: debit cards, credit cards or ATM cards, audio and video cassettes etc
10. What are magnetic keepers?
Ans: A soft iron pieces placed across the ends of a pairs of bar magnets to preserve the magnetism for a long time is called magnetic keepers.

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