P7: THE GENERATOR EFFECT

Question 1

What is the generator effect?

Answer 1

-if an electrical conductor (eg: metal wire) moves in a magnetic field, a current is induced
-it is only a current if the circuit is complete, otherwise a potential difference has been induced

Question 2

How can the size of the induced voltage be increased?

Answer 2

-increasing force
-increasing strength of the magnetic field
-increasing no. of turns of wire in coil
-inserting iron core

Question 3

What does an alternator do and how?

Answer 3

-generates alternating current by rotating a metal coil in magnetic field
-in an alternator, 1 side of the coil moves up during 1 half-turn and then down during the next half-turn
-so the induced current reverses direction every half-turn
-an alternator uses 2 separate commutators that provide continuous connection to the circuit whilst the coil is moving

Question 4

What does a dynamo do and howdoes it work?

Answer 4

-uses generator effect to produce direct current
-involves moving a magnet inside a coil of wire

Question 5

Explain how an alternator generates an AC (5 marks)

Answer 5

-a coil of wire rotates inside magnetic field
-a potential difference is induced in the coil
-as it is a complete circuit, a current is also induced
-every half-turn, the induced current in the coil is reversed therefore producing AC

Question 6

Explain how a dyanmo generates a DC (5 marks)

Answer 6

-a coil of wire rotates inside magnetic field
-a potential difference is induced in the coil
-as it is a complete circuit, a current is also induced
-split ring commutator changes the coil connections every half turn
-as the induced potential difference is about to change direction, the connections are reversed
-this means that the current to the external circuit always flows in the same direction therefore producing DC