magnetism

Question 1

what is a magnet

Answer 1

object which has opposite magnetic poles at each end

Question 2

difference between permanent and temporary magnet

Answer 2

permanent- retains magnetism (bar)

temporary - does not retain magnetism (electromagnet)

Question 3

what is a magnetic field

Answer 3

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

Question 4

magnetic field lines

Answer 4

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

shows direction of force

Question 5

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

Answer 5

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

Question 6

what happens when a compass is brought near a magnet

Answer 6

comoass needle is attracted to south pole of the magnet

Question 7

what is earths magnetic field called

Answer 7

magnetosphere

Question 8

what is magnetic declination

Answer 8

angle between magnetic north pole and geographic “true” north

Question 9

describe earths magnetic field

Answer 9

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

Question 10

how do aurora borealis and aurora australis come about

Answer 10

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

Question 11

how do magnetic storms come about

Answer 11

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

Question 12

ferromagnetic elements

Answer 12

iron
nickel
cobalt

Question 13

curie temperature

Answer 13

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 

Question 14

substance that can be magnetised

Answer 14

ferromagnetic

Question 15

how to magnetise a metal

Answer 15

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

run strong magnet along piece of ferromagnetic material many times

Question 16

everyday uses of soft iron

Answer 16

speakers,telephones

Question 17

hard iron every day uses

Answer 17

bar magnets,motors,televisions

Question 18

how do you affect the force of a magnet

Answer 18

stronger magnets (greater force)
smaller distance (greater force)

Question 19

what do more dense field lines indicate

Answer 19

stronger magnetic field

Question 20

how can a magnet lose its magnetism

Answer 20

heat it above curie temperature, hit with hamma

Question 21

why does compass needle always point to geographic north pole

Answer 21

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

Question 22

uses of electromagnets

Answer 22

motors,speakers,doorbells

Question 23

diff between hard iron and soft iron

Answer 23

soft
temporary,easily magnetised,magnetism easily lost

hard
permanent
hard to magnetise
retains magnetism very well