Physics - Chapter 24 - Magnetism
just as a current carrying wire will deflect a magnetic compass
a magnet will deflect a current carrying wire
surrounding every moving electron is
a magnetic field and a electric field
cosmis rays penetrate your body when
all the time
if a galvanometer is calibrated to measure current its called
ammeter
surrounding every stationary electron is
an electric field
a current carrying coil of wire is
an electro magnet
a common magnet always had
at least two poles
the direction of the force exerted on a moving charge in a magnetic field is
at right angles to the direction of the motion
like kinds of magnetic poles repel while unlike kinds of magnetic poles
attract
when a current carrying wire is bent into a loop, its magnetic field inside the loop
becomes stronger
List two ways that magnets are like electric charges
can attract and repel without touching depending which ends of the magnet are near one another strength of their interaction depends on separation distance between the two magnets
in the atoms of non ferromagnetic materials(iron), the indivual electrons
cancel one another
whereas electric charges can be isolted, magnetic poles
cannot
explain how the effect of magnetic forces on charge particles helps protect earth from cosmic radiation
charged particles from outer space are deflected by earth's magnetic field, reducing the intensity of radiation
magnetic field lines about a current carrying wire
circle the wire in closed loops
the shape of a magnetic field surrounding a current carrying conductor is
circular
what are magnetic domains
clusters of aligned atoms caused from interactions of magnetic field
what causes earth's magnet
convection current
describe some possible explanations for why earth itself is a magnet
convection currents in molten parts of earth's interior
describe a simple electromagnet
current carrying wire with many loops
describe what happens to the magnetic domains in an iron nails that is brought near a strong magnet
domains that are already oriented in that direction of magnetic field grow and domains that are not aligned with the magnet field rotate into alignment
to weaken a bar magnet
drop it, whack it, heat it
two ways to make a permanent magnet weaker
dropped heated
What happens if you break a bar magnet in half and then brea each of the laves in half
each laves will behave as a complete magnet
electric motor
each time the coil makes a half rotation, the direction of the current changes in cyclic fashion to produce continuous rotation
an iron iron is more strongly attracted to the
either the north of south pole
its due to
electric currents
which force field can increase a moving electron's speed
electric field
whihc field can accelerate an electron
electric field magnetic field
two types of electron motion that produce the magnetic field in a bar magnet
electron revolution - electrons revolve around the nucleus electron spin - electrons spin around about their own
which one is more important in terms of the materials overall magnetic field
electron spin
compared to the huge force that attracts an iron tack to a strong magnet, the force that the tack exerts on the magnet is
equally huge
direction of force that a magnetic field exerts on a moving charged particle is always perpendicular to
field lines and current
Where the magnetic field lines are close together,
field strength is great
mechanical to electric
generator
magnetic declination
geographyic and magnetic poes arent same
magnetic field is not due to a
giant magnet in interior
over geologic history the earth's magnetic field
has reversed many times
if you break a bar magnet in half youll
have two magnets
place an iron rod inside a current carrying coil of wire and you
increase the strength of the electromagnet
the most magnetic of these metals is
iron
how do rock strata provide evidence that earth's magnetic field is not stable
iron atoms in a molten state tend to align with earth's magnetic field, when iron soldifies, the direction of earth's field is indicated by orientation f the domain;s in rock
electromagnet
iron bar placed in a current carrying coil
moving charged particles cant be
isolated
particle moves int eh direction neither perpendicular nor parallel to the magnetic field line
less force
earth is a huge
magnet
discrepancy between the orientation of a compass and truth north is called the
magnetic declination
the difference between a piece of ordinary iron and an iron magnet is the alignment of the
magnetic domains
What is the name of the force due to the motion of charged particles
magnetic force
fore that acts between a pair of magnetic poles depends on
magnetic pole strength - separation distance
pigeons navigate primarily
magnetic sensors in their heads
force that acts between a pair of electrically charged particles depends on
magnitude of charge - separation distance
particle moves in a direction perpendicular to the magnetic field lines
maximum force
a current carrying wire in a magnetic field
may be deflected may experience a force
electric to mechanical
motor
magnetism is due to the motion of electrons as they
move around the nucleus and spin on their axes
source of all magnetism
moving electric charge
can magnet poles be isolated like electric poles
no
Every magnet, has a
north and south pole
the conventional direction of magnetic field lines outside a magnet are from
north to south
direction of the magnetic field outside a magnet is from the
north to south pole
if an ordinary iron nail is removed from a strong magnet, the nail will lose its magnetism Why?
ordinary thermal motion causes most or all of the domains in the nail to return to a random alignment
a beam of electrons can pass through a magnetic field without being deflected if the direction of the beam is
parallel to the field lines
a beam of electrons passing through a magnetic field experiences maximum deflection if the direction of the beam is
perpendicular l to the field lines
the force exerted on an electron moving in a magnetic field is maximum when the electron moves
perpendicular to the magnetic field
the force of a magnetic field exerts on a current carrying wire is maximum when the wire is oriented
perpendicular to the magnetic field
force on a wire is maximum when the current is
perpendicular to the magnetic field lines
Regions that produce magnetic forces are called magnetic
poles
the intensity of cosmic rays bombarding the earth's surface is most at the
poles
if a magnet produces a force on a current carrying wire, the wire
produces a force on the magnet
the lift experiences by maglev trains is due to magnetic
repulsion
earth's magnetic field
reverses direction
magnetic poles of earth are widely
separated from geographic poles
magnetic field
space around the magnet
as the number of loops in a current carrying wire is increased, the
stronger the enclosed magnetic field becomes
if the direction of current in the wire is reversed,
the deflecting force on the wire acts in the opposite direction
Where the magnetic field lines are far apart
the field strength is weak
an iron rod becomes magnetic when
the magnetic domains are alligned
why is cosmic ray bombardment greatest at earth;s magnetic poles
the rays approach the earth radially from all directions
the force on an electron moving in a magnetic field will be least when its direction is
the same as the magnetic field direction
if its calibrated to measure electric potential (voltage) is called
voltmere
particle is at rest in the field
zero force
particle moves in a direction parallel to the magnetic field lines
zero force