magnetism Flashcards

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1
Q

what is a magnet

A

object which has opposite magnetic poles at each end

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2
Q

difference between permanent and temporary magnet

A

permanent- retains magnetism (bar)

temporary - does not retain magnetism (electromagnet)

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3
Q

what is a magnetic field

A

region in space where a magnet/ferromagnetic material will experience a force which is magnetic in nature.

area around a magnet where another magnetic material experiences a force

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4
Q

magnetic field lines

A

imaginary lines running from N-S around a magnetic, represent direction compass would point if placed in position

shows direction of force

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5
Q

what will happen if iron filings sprinkled on on top of bar magnet

A

iron filings experience a force as they are in the magnetic field created by the bar magnet.

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6
Q

what happens when a compass is brought near a magnet

A

comoass needle is attracted to south pole of the magnet

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7
Q

what is earths magnetic field called

A

magnetosphere

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8
Q

what is magnetic declination

A

angle between magnetic north pole and geographic “true” north

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9
Q

describe earths magnetic field

A

resembles that of bar magnet
south pole of magnet situated near geographic north pole
magnet poles do not coincide with geograohic poles

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10
Q

how do aurora borealis and aurora australis come about

A

originate from surface of the sun
solar activity
cloud of gas(coronal mass ejection CME) is released
cloud travels to Earth
collides with Earths magnetic field
currents of charged particles generated
(particles have own magnetic field)
interraction between different magnetic fields causes particles to spiral along Earth magnetic field lines into polar regions
(particles have high energies)
collision with N & O2molecules in atmosphere cause air molecules to be charged/ionised
radiate energy in form of auroral light when ionised

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11
Q

how do magnetic storms come about

A

caused by disturbances in earths magnetic field
solar wind (caused by CME)
collides with and compresses magnetosphere
shock of collision releases large amounts of energy into magnetosphere
rapid fluctuations in magnetic field
changing field causes seriouds damage

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12
Q

ferromagnetic elements

A

iron
nickel
cobalt

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13
Q

curie temperature

A

The temperature to which a magnet must be heated to change the alignment of the domains (which are themselves magnetic fields )of the material and hence lose its permanent magnetism 

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14
Q

substance that can be magnetised

A

ferromagnetic

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15
Q

how to magnetise a metal

A

wind wire around a piece of ferromagnetic material and send a current through it

run strong magnet along piece of ferromagnetic material many times

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16
Q

everyday uses of soft iron

A

speakers,telephones

17
Q

hard iron every day uses

A

bar magnets,motors,televisions

18
Q

how do you affect the force of a magnet

A
stronger magnets (greater force)
smaller distance (greater force)
19
Q

what do more dense field lines indicate

A

stronger magnetic field

20
Q

how can a magnet lose its magnetism

A

heat it above curie temperature, hit with hamma

21
Q

why does compass needle always point to geographic north pole

A

a compass is a magnet
earth has a magnetic field with its magnetic south pole near geographic north pole
compass needle attracted to south pole of earths magnetic field

22
Q

uses of electromagnets

A

motors,speakers,doorbells

23
Q

diff between hard iron and soft iron

A

soft
temporary,easily magnetised,magnetism easily lost

hard
permanent
hard to magnetise
retains magnetism very well