P15//2 Flashcards
what happens if an electric conductor cuts through a magnetic field
a potential difference is induced across the ends of the conductor
what is electromagnetic induction
if a magnet is moved into a coil of wire, a potential difference is induced across the ends of the coil
what is the generator effect
if a magnet moves into a coil of wire which is part of a complete circuit a current passes through it
what happens if the direction of movement of the wire is reversed in the generator effect
the polarity of the magnet is reversed and the direction of the potential difference is reversed
how is the size of the pd increased in the generator effect
the speed of movement
strength of magnetic field
number of turns of coils
what is an alternator
alternating current generator
how does an alternator work
a rectangular coil spins in a uniform magnetic field
when is the size of the induced pd greatest and when is it 0
when the plane of the coil is parallel to the direction off the magnetic field
it is 0 when the plane of the coil is perpendicular to the magnetic field
what happens the faster the coil rotates
the higher the frequency and the greater the peak value of alternating current
what is a dynamo
direct current generator
what is different about a dynamo to a alternator
the dynamo has a split ring commutator instead of slip rings and it always generates a positive pd
what does a transformer consist of
two coils of insulated wire , the primary and secondary coil
the coils wind around the same iron core
how does a transformer work
when an alternating current passes through the primary coil, it produces an alternating magnetic field in the core
the alternating magnetic field lines pass through the secondary coil and induce an alternating pd so an ac is produced
what is a step up and step down transformer
a step up has more coils in its secondary coil
a step down has more coils in its primary coil
