magnetism Flashcards
how many poles does every magnet have
2
what are the names of the poles that magnets have
north and south
where is the magnetic field the strongest
at the poles of the magnet
opposite poles…
attract
like poles….
repel
what happens when two magnets are brought close together
the magnets exert a force on one another
what is a magnetic field
the region around a magnet there it will exert a force on another magnet/ magnetic matroe;
how many magnetic matriels are there
4
what are the magnntic matriels
iron, steel, cobalt and nickel
what two things can be used to investigate a magnetic
- plotting compass - align compass around bar magnet
2, iron fillings
where is the magnetic field stronger
where the firled lines are close together
what two things does a uniform magnetic field have
the same strenth and same direction
when does a uniform fiekd have the same strength and same direction
when north and south are close together
what does earth have
a magnetoic field
the north ppoel of earth is the..
earths magnetic south pole
where will a compass needdle always pount
in the direction of the earths magnetic field
where does the north pole of a compass point
to the earth;s south poel
what does a permant magnet do
it can produce its own mangetic field and always has a north south pole
if a magnet is permaant, what can it be attracted and repeled by
another magnet
when does an induced magnet become magnetic
when it is placed into a magnet field
if a magnet is induced, what will it only be attracgted to
permanet magnet
what happens when current flows throufh a wire
a magnetic fiekd will be produced around the wire
what does the strentgth of the magnetic field depend on
the size of the current and the distance from the wire
what is the right hand grip rule
- thumb shows the directiion of current
- where your fingger coils shpws the direction of the magnetic field
what happens to the direction of the magnetic fueld when the current is reverse
the direction of the magnetic field will change
what is a solenoid
a coil of wire attached to a power supply
hnow do you increase the strenth of the magnetic field produced by a solenoid
- using more turns of wire
- moving turns closer togehter
- putting an iron core into the middle of the solenoid
how is an electromagnet created
when an iron core is placed into a solenoid
what happens inside of a solenoid
- uniform magnetic field
- evenly spaved out
- pointing in same direction
- magnetic field is strongest
- fieldlines are cliser tigether
what happens outside of the soldenoid
- not unfirom
- not evenky soaced out
3, field lines change directuons - magnetic field is weaker
what is flemmings leftr hand rule
- second fingure - direction of magnetuic field
- middle - direction of current
- thumb - direction of the force
what happens when a conductor carrying a current is placed in a magnetic field
the conductor and the magnet producing the field will exert a foce on one another (unless conductor is parallel to field lines
when is a force only exerted on a conductor
if the conductor is perpendircular to the filed lines
what happens when the wire iis parallel to the field lines
there is no magnetic force exerted on it
what does a motor do
produces a force that moves things
what does battery produces
direct current
where does convectional current flow from
postive terminal of the battery to the negative
how did the direction of the rotatipon of the motor be reversed
- reverse the direction of magnetic field
- reverse the polarity of the battery
what causes the coil to rorate in a clockwise direction
when the left side of the coil is forced upwards and the right side is forced downwards in a motor
when a coil of wire is carrying current, where is it placed
around the permanent magnet
the magnetic field around the coil of wire and what will interact
and that of the permanement magnet will interact with each other
what causes the coil of wire to rotate
when the magnetic field around the coil of wire and that of the permanent magnet interact with each other and exert a force on the coil of wire
what is the motor effect
- when a coil of wire is carrying current it is placed around the permanent magnet
2 the magnetic field around the coil of wire and that of the permanent magnet interact with each other - and exert a force on the coil of wire causing it to rotate
how do you maintain the rotation of the coil of wire in the motor effect
a split ring commutator is used
what does a split ring commutator do
it rotates with the coil between the carbon brushes
what happens each time the coil passes the vertical positon, split ring commutator
the direction in which current flows around the coil
what allows for continous rotation of the coil
each time the coil passes the vertical position, the direction which current flows around the coil changes
what way is the coil of wire supposed to be rotating
clockwise, everytime it goes past the vertucal position
what is the role of a loud speaker
to amplify sound
what is inside a loudspeaker
a magnet and there are coils of wire around the magnet
how does a loud speaker wordk
1, when a current flows through the coil both the coil and the speaker come to experience a force
2. when the direction of the current through the coil reverses so does the direction of the force exerted on it and the speaker cone
3. supplying an alternating electrical input signal to the speaker will cause the cone to vibrate back and forth producing a sound wave
how do you increase the size of the uunduced pd
- move the magnet more quickly
- use a stronger magnet
- increase the number of turns on the coil
- increase the area of the coil
what do you need to generate electricity
magnet, wire and movement
how do yyou reverse the direction of induced pd
- reverse the drirection in which the magnet is moved
- reverse the magnetic field direction
when does magneticc flux density change
when the wire cuts through it
when is a magnetic field generated
when an induced current flows through a wire
what will always acy so as to oppose the change that created it
an induced magnetic field
what is a repulsive force between
the north poel of the magnet and the induced north pole of the coil
work myst be done aganist thhe repilsive force in order to push the magnet towards the coil, as a result of what
the repulsive force betweem the north pole of the magnet and the induced north pole of the coil
what happens when a wire is moved in between two magnets
an induced p.d is created
what happpens when a wire is connected in a complete circuit
an induced current is produced
what happens when a coil of wire is moved in between two magnets
electricity is generfated
what is the role of an alternator
to allow kinetic energy of the a rotating coil to produce electricity
what happens when the regtangular coil is rotated
it cuts throught the magnetic flux of the peranemet magnetic filed. this causes alternating current to be induced
how can the inuced pd be increase in the alternator
1, rotating the coil more quickly
2. increasing the strength of the magnetic field
3. increasing the number of turns
4. increasing the area of the coil
what is each end of the coil permanent attached to
one of the slip rings
what happens when a given side of the coil is moving upwards through the magnetic field
current will flow through it in one direction
when the same side of the coil is moving downwards through the magnetic field, what happens
current will flow through it in the opposite direction
how many times does the direction of the current alterantes during each full rotation of the coil
2
what is the role of a microphone
magnifices sound by producing an alternate current
how does a microphone work
- when a sound waves ishit onto the surface of the microphone the flexible diaphragm vibrates back and forth
- this causes the coil which is attached to it too vobrate back and forth
- an alternating current is induced
- this alternating current can be amplified before being used to drive a loudspeaker
