Alternators

Question 1

What does an alternator do?

Answer 1

Allows for the KE of a rotating coil to be converted to the electrical energy of an induced electric current

Question 2

How does an alternator work?

Answer 2

1) When the rectangular coil is rotated, it cuts through the lines of magnetic flux of the permanent magnetic field
2) This causes an AC to be induced in the coil (and in the connected circuit)

Question 3

How do the slip rings in an alternator work?

Answer 3

Each end of the coil is permanently attached to one end of the slip rings. When a given side of the coil is moving upwards through the magnetic field, current will flow through it in one direction. When the same side of the coil is moving downwards through the magnetic field, current will flow through in the opposite direction. In this way, the current direction alternates twice during each full rotation of the coil

Question 4

Alternator p.d-time graphs

Answer 4

P.d rises to a high voltage when the direction of the coil is parallel to the magnetic field lines and decreases back to 0 as direction changes to become perpendicular to the magnetic field lines. This repeats during the other half of this rotation but in the opposite direction (downwards)

Question 5

How does a moving-coil microphone work?

Answer 5

1) When a sound wave is incident onto the surface of the microphone, the flexible diaphragm vibrates back and fourth
2) This causes the coil, which it is attached to, to vibrate
3) An AC is induced in the coil which can be amplified before being used to drive a loudspeaker