Motor effect/induction Flashcards
What is the motor effect?
when a current is passed through a wire placed in a magnetic field, a force is produced which acts on the wire
Fleming’s left hand rule
- thuMb: Movement/ force
- ForeFInger: field
- seCond finger: current
When is the force at a maximum?
wire perpendicular to field lines
How do you increase the force?
- increasing current
- increasing field strength
Uses of motor effect
- electric motors
- loudspeakers
How does a loudspeaker work?
ac. current (produced by an amplifier) passes through a coil inside a magnet
- results in alternating forces on the coil which moves it up and down
- transfers vibrations to the air
- creating soundwaves
describe an electric DC motor
consists of a coil of wire which is free to rotate in a magnetic field about an axle. it is connected to a split ring commutator which allows current to pass through the coil with a pair of brushes
When is the turning effect zero?
when the coil is parallel to magnetic field
How do you make the motor spin faster?
- increase strength of field
- increase number of turns
- increase current
What is induction used for?
generating electricity
What is induction?
when a conductor moves through a magnetic field, cutting field lines, the p.d. is induced in the wire
How to increase the size of induced. pd.
- increase speed of movement
- increase strength of magnetic field
- increase number of turns on coil
- increasing area of coil
How does a bicycle lamp work?
- magnet is spun by wheels
- magnetic field lines cut by wire - induces p.d.
- current flows through wire
What type of voltage does induction produce?
AC voltage
- minimum output - when coil is parallel to direction of current
- maximum output - when coil is perpendicular to direction of current
