unit 14-magnets

Question 1

what is a magnet ?

Answer 1

the term magnet is derived from magnetite which has the property of attracting Iron and other magnetic substances towards itself

Question 2

how are magnets classified ?

Answer 2

magnets are classified on the basis of their origin

Question 3

what is magnetism ?

Answer 3

magnetism is a force of attraction and repulsion that acts between certain objects

Question 4

what are the two types of magnets

Answer 4

the two types of magnets are natural and artificial magnets

Question 5

what are natural magnets ? explain in depth

Answer 5

the ore of magnetite or loadstone are found in irregular shapes , they are called natural magnets because they occur naturally , their magnetic strength is weak , all natural magnets are permanent magnets .

Question 6

what are artificial magnets ? explain in depth ?

Answer 6

when magnets are made by man , they are called artificial magnets , artificial magnets are prepared by using elements such as iron or steel alloys, they much stronger in comparison to natural magnets, depending on the requirement, these magnets are made in various shapes and sizes. Some examples are: horseshoe magnets, ring magnet and bar magnet.

Question 7

what are magnetic substances ?

Answer 7

the substances that get attracted to a magnet are called magnetic substances , ex:Iron,steel,nickel,cobalt and their alloys are a few examples

Question 8

what are non-magnetic substances ?

Answer 8

the substances that do not get attracted to/by a magnet are called non-magnetic substances, for example-gold,silver,aluminium,glass are a few examples of non-magnetic susbtances

Question 9

what are the properties of a magnet?

Answer 9

1-poles of a magnet
2-poles exist in pairs
3-attractive property
4-attraction and repulsion between magnets
5-directive property
6-magnetic induction

Question 10

explain the first property of a magnet

Answer 10

any magnet regardless of its shape has two ends called poles, namely the north pole and the south pole, where the magnetic effect is strongest, the magnetic strength decreases at the center, in some magnets the north pole is shown with a white dot

Question 11

explain the second property of a magnet

Answer 11

the second property of a magnet is that poles exist in pairs, if we divide a magnet into two parts then each behaves like a magnet having both the poles, if we further divide the pieces into more parts , then each part will again behave like a complete magnet with opposite polarities at the two ends , therefore poles of magnet always exist in pairs

Question 12

explain the third property of a magnet

Answer 12

the third property of a magnet is the attractive property, when a magnet is brought close to or in contact with other magnetic substances, it attracts them. This property of a magnet is called the attractive property of a magnet

Question 13

explain the fourth property of a magnet

Answer 13

the fourth property of a magnet is called attraction and repulsion between magnets.
like poles of a magnet repel, ex-north-north and south-south. whereas unlike poles of a a magnet attract, ex-north-south south-north,
if we pick up 2 magnets and bring either of their north pole or south pole together, you will feel your hands being pushed away even though the magnets are not touching, the strength of the push increases as you bring two similar poles closer to each other.if you bring the north pole of a magnet to the south pole of a magnet you will feel your hands being pulled together as different poles attract each other, the strength of the pole increases as the poles get closer to each other

Question 14

explain the fifth property of a magnet

Answer 14

the fifth property of a magnet is called the directive property of a magnet, a freely suspended magnet always rests in north-south direction, this property of a magnet is called directive property of a magnet.

Question 15

what is the sixth property of a a magnet ?

Answer 15

the process by which a substances like iron becomes magnetized when placed in contact or brought near to a magnet is called magnetic induction, in this process the iron gets demagnetized as soon as it loses contact with the magnet.

Question 16

what is the sure test of a magnet ?

Answer 16

repulsion takes place only between two like poles of a magnet, whereas attraction takes place between two unlike poles of a magnet and also between a magnet and a magnetic substance.by attraction, it cannot be identified if the substance is a magnet or not, therefore repulsion is the sure test of magnetism.

Question 17

what are the

two types of magnets ? and how are they classified ?

Answer 17

the other two types of magnets are permanent and temporary magnets, they are divided on the basis of nature and strength.

Question 18

explain temporary magnets

Answer 18

unlike permanent magnets , temporary magnets can not remain magnetized on their own, soft magnetic materials like iron and nickel will not attract paper clips after a strong external magnetic field has been removed, it can easily be demagnetized, its strength and polarity can both be altered, permanent magnets differ from temporary magnets by their ability to remain magnetized.

Question 18

explain permanent magnets

Answer 18

permanent magnets are made from hard magnetic materials that have the ability to become magnetized and remain magnetized, permanent magnets are prepared from steel.Its magnetic strength and polarities can not be altered

Question 18

what is a magnetic field

Answer 18

the space around a magnet where the magnetic force of attraction is felt the maximum is called magnetic field of magnet. the magnetic field of a magnet is represented by magnetic field lines

Question 19

what are the 4 properties of magnetic field lines ?

Answer 19

1- the magnetic field line is directed from the north pole to the south pole outside the magnet and from south pole to north pole inside of the magnet
2-it is a closed and continuous curve
3-it is crowed near the pole where the field is strong and far from the magnet where the field is weak
4- it never intersects each other

Question 20

what is a a magnetic compass ?

Answer 20

a magnetic compass is constructed by placing a magnetized needle on the pivot point which can rotate freely in all of the directions that are marked on the dial, the needle indicates the north and south direction, it is used to locate the direction of any place

Question 21

explain the earths magnetic field

Answer 21

in about 1600 A.D, William gilbert, an English physician, performed experiments and suggested that the earth itself behaves like a magnet that causes a freely suspended magnet( or a magnetic needle) to always point in a particular direction, i.e.-north to south
a freely suspended bar magnet always points in the geographic north-south direction even in the absence of any other magnet visible to us

Question 22

how are magnets made ?

Answer 22

magnets ae made by exposing metals like iron, steel or nickel to magnetic fields

Question 23

what are the 3 methods of making magnets ?

Answer 23

1-single touch
2-double touch
3-eletrical method

Question 24

explain single touch method

Answer 24

this is the simplest and also most convenient method to make a magnet that does not posses a strong magnetic field of attraction, an iron or steel bar can be magnetized by rubbing it with a permanent magnet.

Question 25

what is the double touch method ?

Answer 25

this method is similar to the single touch method .in this method two permanent magnets are taken to magnetize metals like iron steel or nickel and rubbing it in opposite directions

Question 26

electrical method

Answer 26

strong magnets are made by the electrical method, a magnet of this kind is also called a electromagnet

Question 27

what are electromagnets ?

Answer 27

an electromagnet is a type of magnet in which the magnetic field is produced by passing an electric current. electromagnets usually consist of a insulated wire wound around a soft iron. A current through the wire creates a magnetic field and the soft iron bar behaves like a magnet.one end of the bar becomes the north pole and the other end becomes the south pole. If the current in the coil is turned off the soft iron bar will quickly demagnetize, so an electromagnet is a temporary magnet

Question 28

what are the uses of electromagnets ?

Answer 28

electromagnets come in all shapes ad sizes, from small ones that make doorbells to enormous magnets tat pick entire cars, they are widely used in devices like motors, generators, relays, cranes, loud speakers, MRI machines etc. strong electromagnets are used in scrap yards for loading and unloading heavy metal scraps. they are used in the maglev trains, in maglev trains, the magnets are used on the tracks. these types of trains work on the force of repulsion of the magnets

Question 29

how do we care and store magnets

Answer 29

1-use a keeper
a keeper is a piece of iron that is temporarily added between the north and south poles of a magnet to prevent it from de-magnetizing
2-store in pairs
storage of magnets in pairs prevents the two south or two north poles to come in contact, if the two poles continuously repel each other the magnetic strength will be weakened
3- store in a dry area
magnets can corrode very easily if stored in a damp area

Question 30

how do we de-magnetize a magnet ?

Answer 30

1-by rough handing and hammering
2-by heating the magnet on a high temperature
3-by dropping the magnet repeatedly from a height on a hard surface
4-by passing high alternating current through it
4-by bringing it in contact with other magnets repeatedly