magnetism Flashcards
(23 cards)
what is a magnet
object which has opposite magnetic poles at each end
difference between permanent and temporary magnet
permanent- retains magnetism (bar)
temporary - does not retain magnetism (electromagnet)
what is a magnetic field
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
magnetic field lines
imaginary lines running from N-S around a magnetic, represent direction compass would point if placed in position
shows direction of force
what will happen if iron filings sprinkled on on top of bar magnet
iron filings experience a force as they are in the magnetic field created by the bar magnet.
what happens when a compass is brought near a magnet
comoass needle is attracted to south pole of the magnet
what is earths magnetic field called
magnetosphere
what is magnetic declination
angle between magnetic north pole and geographic “true” north
describe earths magnetic field
resembles that of bar magnet
south pole of magnet situated near geographic north pole
magnet poles do not coincide with geograohic poles
how do aurora borealis and aurora australis come about
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
how do magnetic storms come about
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
ferromagnetic elements
iron
nickel
cobalt
curie temperature
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 
substance that can be magnetised
ferromagnetic
how to magnetise a metal
wind wire around a piece of ferromagnetic material and send a current through it
run strong magnet along piece of ferromagnetic material many times
everyday uses of soft iron
speakers,telephones
hard iron every day uses
bar magnets,motors,televisions
how do you affect the force of a magnet
stronger magnets (greater force) smaller distance (greater force)
what do more dense field lines indicate
stronger magnetic field
how can a magnet lose its magnetism
heat it above curie temperature, hit with hamma
why does compass needle always point to geographic north pole
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
uses of electromagnets
motors,speakers,doorbells
diff between hard iron and soft iron
soft
temporary,easily magnetised,magnetism easily lost
hard
permanent
hard to magnetise
retains magnetism very well
