FUN WITH MAGNETS | SPEED NOTES | SCIENCE | CBSE | CLASS 6

CBSE Class–VI Subject Science Revision Notes CHAPTER – 13 Fun withMagnets Magnets: Materials that attract iron, nickel and cobalt. Natural magnet is called Iodestone or magnetite. Magnetite is a natural magnet. Magnet attracts materials like iron, nickel, cobalt. These are called magnetic materials. Materials that arenot attracted towards magnet are called non-magnetic ex. aer,glass,cloth,lastic,rubber etc. Magnetic force : The force bymeans of whicha magnet attracts objects towards itself . Poles of a magnet :- The ends ofthe magnet wheremaximum iron filings get collected arecalled the poles. North pole :- The end pointing towars north is called thenorth seeking endor the North pole. South pole :-The endpointing towards southis calle thesouth seeking or the South pole. A freely suspended magnet always aligns in N-S direction. Like poles repel , andunlike poles attract each other.

DIFFERNT TYPES AND SHAPE OFMAGNETS Bar magnet Ball-ended magnet (Dumb-bell ) Horseshoe magnet Cylindrical magnet Magnetic needle Artificial magnet Loadstone ( natural magnet) ring ordisc shape magnet

Temporary magnets :- Temporary magnets last or a short time.( Iron bar magnets) Permanent magnets :- Permanent magnets last for a long time.They are madefrom a steel or analloy known asAlNiCo, a combination of aluminium,nickel ancobalt. Classification ofsubstances based onattraction to magnets: Magnetic Substances: Materials which get attracted towards magnets. Example: copper, iron, nickel, etc. Non-magnetic Substances: Materials which donot get attracted towards magnets. Example: wood,paper, plastic andmost metals.

Methods tomake your ownMagnet: Single Touch Method: Whena magnet isused to ruban iron object along it's length, the starting from one end to another end like combing one's hair, the iron object gets magnetised. Double Touch Method: When an iron bar ( object ) is rubbed by two powerfull bar magnets of equal strength with their opposite poles at thecentre, in opposite direction , thebar or theobject becomes amagnet. Using Electric Current: The barto be magnetized is placed inside the coils ofa conductor andcurrent is passed through these coils of wire.

Properties ofMagnet: A magnet has two poles – north pole and south pole. Similar poles repel eachother. Opposite poles attract each other. Magnetic poles always exist in pairs. There is nomagnet like monopolar magnet. magnet isalways bipolar.

Applications of Magnet: Compass needle: The compasss is a small glasscase containing a magnetised neelepivoted on analuminium nail. Theneedle is freeto rotate. Itpoints north-south because the earth is

also a giant magnet. The compass lines up withthe earth’s magnetic field. Used in factories for lifting heavy masses of iron like scrap iron. Call bellsan door chimes use elctromagnet. Loudspeaker have parmanent magnet Used by surgeons in hospitals to remove steelsplinters from thewounds. Used in the construction of telephones, electric bells, etc. Used to separate iron and steel from non-magnetic materials.

DEMAGNETISATION , loss of magnetic proprty A magnet maylose its magnetic property when itis , hammered heated, or dropped with aforce and itstrikes against a hard substance. When twobar magnets arenot stored withtheir like olespointing in thesame direction , each polewill destroy theother by induction.

TAKING CAREOF MAGNETS When not in use themagnets should be stored inboxes made fromnon-magnetic materials like cardboard or wood. magnets should be protected with 'keepers '.