15.4-6 Flashcards
what is the motor effect
a force can act on a wire ( or any other conductor) in a magnetic field when a current is passed through the wire.
how can the size of force in the motor effect be increased
increasing current and use a stronger magnet, more turns in coil
how does the size of force depend on the angle between the wire and the magnetic field lines in motor effect
the force is greatest when the wire is perpendicular to the field line (cuts through them all). Zero when the force is parallel ( not cutting through any)
what does flemings left hand rule show
direction of force
where do the first finger, second finger and thumb point in flemings left hand rule
first finger - north to south, second finger- current, thumb- movement
what is magnetic flux density
measure of the strength of the magnetic field
what does the force on the conductor depend on in this diagram
current in the conductor, length of the conductor, magnetic flux density of the magnetic field
how do you change the speed of an electric motor
change current
how do you change the direction of an electric motor
reverse current
why is graphite used in a motor to give the coil electricity
it conducts electricity and is very slippery so causes little friction when it is in contact with the rotating commutator
what does a split ring commutator do
swaps the positive and negative connections every half turn, this means the direction of current swaps every half turn, this means the forces acting on the coil will always be acting in the same direction.
what does a generator contain
coils of wire that spin in a magnetic field
what is electromagnetic induction
when a potential difference is induced across the ends of the wire when it crosses through the magnetic field lines.
what is the generator effect
if a conductor is part of a complete circuit, the induced potential difference makes an electric current pass around the circuit.
what does a stronger magnet do in a generator
the induced potential difference and current will be higher
why does the ammeter move her
the movement of the bar magnet causes an induced potential difference in the coil, this creates a current as it is a complete circuit
how do you increase the current and potential difference is this
use a stronger magnet
In this picture, when the magnet is removed from the coil when does the ammeter point in the other direction
the induced potential difference acts in the opposite direction, so the induced current is in the opposite direction
when someone is moving a magnet through a coil what is electricity as a result of
work done by the person`
what is an alternator
alternating current generator
what is an alternator made up of
a rectangular coil that is forced to spin in a uniform magnetic field
how does a alternator work
Magnetic Field & Coil – A coil of wire rotates within a magnetic field.
Electromagnetic Induction – As the coil spins, the magnetic field cuts through the wire, inducing a current.
Alternating Current (AC) – The direction of current changes every half-turn, producing an AC output.
Slip Rings & Brushes – These allow continuous rotation while maintaining an electrical connection.
Describe how the induced potential difference varies as the coil rotates.
The induced potential difference varies as the coil rotates, reaching its peak value when the coil’s plane is parallel to the magnetic field, and becoming zero when the plane is perpendicular to the magnetic field lines.
Explain the conditions under which the induced potential difference is at its peak value.
The induced potential difference is at its peak value when the plane of the coil is parallel to the direction of the magnetic field, allowing the sides of the coil to cross directly through the magnetic field lines.
