Physics ICSE Class 6 Important Questions Chapter 8 Magnetism
Practice Questions
Question 1.
Name two types of artificial magnets.
Answer:
- Temporary magnets
- Permanent magnets
Question 2.
What does ALNICO stand for ?
Answer:
ALNICO – aluminium, nickel and cobalt mixture (alloy)
Question 3.
Name two rocks (ores) showing magnetic properties.
Answer:
Lodestone and magnetite
Question 4.
State properties of a magnet.
Answer:
Properties of a magnet :
- Attractive property – Magnets attract object made of iron,
cobalt and nickel (magnetic substances) - Poles of a magnet – Each magnet has two poles, namely the north pole and the south pole. These poles always exist in pairs.
- Directive property – A freely suspended magnet always points towards the geographical north-south direction.
- The attractive power of a magnet reduces as we move from the ends towards the centre of the magnet, i.e., it is maximum at the ends and practically zero in the centre.
- Like poles repel and unlike poles attract each other, when two magnets are brought close to each other.
Question 5.
Define –
1. magnetic north pole
2. magnetic south pole
Answer:
1. The point at the end of the freely suspended magnet that points towards the geographic north pole of the earth is called the magnetic north pole.
2. The point at the end of the freely suspended magnet that points towards the geographic south pole of the earth is called the magnetic south pole.
Question 6.
Give few uses of electromagnet.
Answer:
- In industries and shipyards to lift heavy loads.
- To separate iron and steel objects from heaps of metal scrap.
- In constructing electric bells, electric motors, telephones, generators, etc.
Question 7.
What is self-demagnetization ?
Answer:
If the poles of magnets are left free for a long time, they tend to become weaker. This is called self-demagnetization. Also when two magnets are kept together, there will be mutual attraction or repulsion and magnets lose their magnetic strength over time.
Question 8.
List few uses of magnets.
Answer:
- Magnets are used in magnetic compasses and used for navigation purpose.
- Used in computers, telephones, doorbells, etc.
- Used as stick-on door closers in refrigerators.
- Small magnets are used by doctors to remove iron splinters from eyes.
Question 9.
Why does a magnet show directive property ?
Or
Why a freely suspended magnets always comes to rest in the north-south direction ?
Answer:
This is because the earth also behaves like a huge magnet. The imaginary bar magnet of the earth is placed in such a way that the north pole of this imaginary magnet is geographic south pole of the earth while the south pole of the imaginary magnet is near the geographic north pole of the earth.
Question 10.
Fill in the blanks :
(i) The property of a magnet to attract metals is called ……………
Answer:
The property of a magnet to attract metals is called magnetism.
(ii) A magnet attracts magnetic substances by exerting a force called the …………
Answer:
A magnet attracts magnetic substances by exerting a force called the magnetic force.
(iii) When brought close together, unlike poles of two magnets …………. each other.
Answer:
When brought close together, unlike poles of two magnets attract each other.
(iv) ………….. is the temporary magnetization of a magnetic substance under the influence of a magnetized force.
Answer:
Magnetic induction is the temporary magnetization of a magnetic substance under, the influence of a magnetized force.
(v) Magnets should be stored using ……………
Answer:
Magnets should be stored using magnetic keepers.
(vi) While storing p&r magnets, two bar magnets are placed side by side with their …………. poles at the same end.
Answer:
While storing bar magnets, two bar magnets are placed side by side with their opposite poles at the same end.
ICSE Class 6 Physics Important Questions