Motors, electromagnetic induction and generators. Flashcards
The force gets bigger if the…
current or magnetic field is made bigger.
Flemings left hand rule.
thuMb= Motion
FIrst finger= FIeld
seCond finger= Current
4 factors to speed up the simple electric motor.
more current, more turns on the coil,stronger magnetic field and a soft iron core in the coil.
why does the coil in a magnetic field rotate?
coil is on a spindle which works one up, one down.
Split ring commutator
swaps the contacts every half turn to keep the motor rotating in the same direction.
How can the direction of the motor be reversed?
swapping the polarity of the DC supply or swapping over the magnetic poles
Electromagnetic induction
The creation of voltage (and maybe current) in a wire which is experiencing a change in magnetic field.
Induction
creation
How can you make magnetic induction?
By moving a magnetic in a coil of wire or by moving a conductor in a magnetic field .
for a bigger peak voltage you must increase…
The strength of the magnet, the area of the coil, the number of turns on the coil, the speed of the movement.
What do generators use instead of a split ring commutator?
slip rings and brushes.
Are generators AC or DC?
AC
What is the difference with dynamos?
you turn the magnet instead of the coil.
How do dynamos work?
The cog wheel is positioned so it touches one of the wheels, as the wheel moves round, it turns the cog which is attracted to the magnet.
