Fun with Magnets
Magnet: a material that attracts any other magnetic material
Magnetic field: the space around a magnet, in which the magnetic effect is in the form of attraction or repulsion and can be experienced by a magnetic material demagnetization: the loss in the strength of a magnetic field is demagnetization
North Pole: the end of a freely hanging magnet which points towards the north
South Pole: the end of a freely hanging magnet which points towards the south
Magnetic materials: materials which are attracted by a magnet
Magnetic compass: an instrument having a magnet that is used to find directions
Temporary magnet: a magnet that retains its magnetic properties for a short period of time
Permanent magnet: a magnet that retains its magnetic properties for a long period of time
POINTS TO REMEMBER
• A lodestone or a piece of magnetite is a natural magnet.
• Magnetic poles occur in a pair.
• Magnet has two poles – a north pole and south pole.
• The earth acts as a huge magnet.
• A magnet can be demagnetized by hammering.
• The two poles of a magnet repel when their like poles face each other and attract each other when unlike poles are brought near.
• The two poles of a magnet are inseparable.
• Magnetic attraction is maximum at the poles.
• Electromagnets are used in bells, telephones, loudspeakers, motors and several other electrical devices.
• Materials that are not attracted by a magnet are called non-magnetic materials like paper, plastic, wood, stainless steel, leather, cloth, etc.
Multiple Choice Questions
1. Which of the following is preferred to make an electromagnet?
(b) Soft iron
(c) Stainless steel
2. The poles of a magnet are located at its
(a) upper surface
(b) middle point
(d) lower surface
3. A magnet can attract a
(a) copper plate
(b) iron ring
(c) rubber band
(d) glass rod
4. The magnetic compass is used by
(d) all of these
5. The two ends of a bar magnet are
6. A magnet loses its magnetic property by
7. A freely suspended magnet points in the which direction
(c) only north
(d) only south
8. Which of the following makes use of a magnet?
(a) a shirt button
(b) a screwdriver
(c) a door stopper
(d) a can opener
9. Which one of the following items cannot be picked up by a magnet?
(a) Paper clips
(c) Aluminum foils
(d) Iron nails
1. (b) 2. (c) 3. (b) 4. (d) 5. (c) 6. (c) 7. (a) 8. (c) 9. (c).
Very Short Answer Type Questions.
1. Name a natural material that possesses the properties of a magnet.
2. Name two methods of making magnets.
3. Name any three items in which magnets are used.
4. What name is given to the ends of a magnet where the attraction is strongest?
5. Which of the following materials are not attracted to a magnet? wood, nickel, copper, steel, aluminium,
6. Name an instrument which is used to find directions.
7. Which of the following are stored in pairs: horseshoe magnets or bar magnets?
8. Name the material that is used to make a permanent magnet.
9. What happens when the N-Pole of a magnet is brought near to the N-Pole of a suspended magnet?
2. The three methods of making magnets are:
(a) Single touch method
(b) Double touch method
(c) Electrical method
3. Compass, refrigerator doors, doors of wooden shelf
5. Wood, steel
6. Magnetic compass
7. Horseshoe magnets
8. The material that is used to make a permanent magnet is from mixtures of iron, cobalt or nickel with other materials.
9. The poles repel each other.
Fill in the blanks with suitable words.
(a) The mineral called magnetite is mainly composed of oxides of————-.
(b) Materials that are not———— by magnets are called non-magnetic materials.
(c) An electromagnet is a———– magnet.
(d) The pull exerted by a magnet or magnetic substance is called————-.
(a) The mineral called magnetite is mainly composed of oxides of iron.
(b) Materials that are not attracted by magnets are called non-magnetic materials.
(c) An electromagnet is a permanent magnet.
(d) The pull exerted by a magnet or magnetic substance is called magnetic pull.
State whether ‘True’ or ‘False’.
(a) The unlike poles of magnets repel and the like poles attract each other.
(b) The two poles of magnets can be easily separated.
(c) A bar magnet is the strongest at the poles.
(d) The heating of a magnet does not demagnetize it.
(e) All metals are magnetic in nature.
(f) Rubber is a magnetic substance.
(g) Magnetic compass helps in knowing the direction.
(h) The soft iron pieces used to store magnets are called Keepers.
(a) False, (b) True, (c) True, (d) False (e) True, (f) False, (g) True, (h) True.