Section 6 - Electric Motors And Loudspeaker Flashcards
Describe how a simple D.C. electric motor works.
Diagram on page 66.
Why does the coil rotate?
Because it’s on a spindle and the force acts one up and one down giving the rotation.
How can you reverse the direction of the motor?
Either by swapping polarity of the d.c. supply or swapping the magnetic poles over.
What does the split ring commutator do?
It is a clever way of swapping the contacts every half turn to keep the motor rotating in the same direction.
How can you speed up the motor?
More current
More turns on the coil
Stronger magnetic field
A soft iron core in the coil
How do electric speakers work?
They work because of the motor effect.
A.C. Signals from an amplifier are fed to a coil of wire in the speaker which is wrapped around the base of the cone.
Coil is surrounded by permanent magnet, so the signals cause a force on the coil which makes it move back and forth.
This makes the cone vibrate which creates sounds.
How does a loudspeaker look?
Go to page 66
