P18 Induced potential and transformers

Question 1

2 ways potential difference is induced in a conductor

Answer 1

Conductor moves relative to a magnetic field
Magnetic field around the conductor is changing

Question 2

How can the direction of an induced potential different or current be reversed?

Answer 2

Reverse the movement of the magnet
Reverse the polarity of the magnet

Question 3

What affects the size of an induced potential difference or current?

Answer 3

Speed of movement
Strength of magnetic field
Number of turns in coil

Question 4

How does an alternator make use of the generator effect?

Answer 4

Produces alternate current

Question 5

What type of current is produced in a dynamo?

Answer 5

Direct current

Question 6

How does a dynamo keep the current flowing in the same direction?

Answer 6

A slip ring commutator makes the ends of the coil swap contacts with the circuit every half turn/

Question 7

How does a microphone use the generator effect?

Answer 7

Converts pressure variations in sound waves in to variations in electrical current.

Question 8

What does a transformer do?

Answer 8

Changes the magnitude of alternating p.d

Question 9

What does a basic transformer consist of?

Answer 9

2 coils of wire wound around an iron core

Question 10

Why is iron used for the core of a transformer?

Answer 10

Iron is easily magnetised

Question 11

How does a transformer work?

Answer 11

Alternating p.d across a primary coil produces an alternating magnetic field in the iron core.

This induces an alternating p.d in the secondary coil.

Question 12

Which type of transformer has more turns on its secondary coil than on its primary coil?

Answer 12

Step up transformer

Question 13

Which type of transformer has more turns on its primary coil than on its secondary coil?

Answer 13

Step down transformer

Question 14

What is the efficiency of a transformer if the power outputs of both coils are the same?

Answer 14

100%