Electromagnetic Induction and Transformers
92 questions· page 1 of 10
An alternating current (a.c.) generator is connected to an oscilloscope.
The diagram shows the trace produced on the oscilloscope screen.
What are possible angles between the plane of the coil and the magnetic field direction at the times represented by points 1, 2 and 3?
Options
| 1 | 2 | 3 | |
|---|---|---|---|
| A | |||
| B | |||
| C | |||
| D |
A step-up transformer is connected between a power station and a long-distance electricity transmission cable.
What is the purpose of the step-up transformer, and does it operate using alternating current (a.c.) or using direct current (d.c.)?
Options
| purpose of a step-up transformer | current used | |
|---|---|---|
| A | to decrease the current in the cable | d.c. |
| B | to decrease the current in the cable | a.c. |
| C | to increase the current in the cable | d.c. |
| D | to increase the current in the cable | a.c. |
A square coil is placed in a horizontal uniform magnetic field. The plane of the coil is perpendicular to the magnetic field.
The coil is now rotated about an axis through P at a steady rate. The coil rotates through .
Which diagram shows how the electromotive force (e.m.f.) induced in the coil varies as it rotates through ?
Options
A transformer is used to power a lamp.
There are more turns on the secondary coil than on the primary coil.
Which statement is correct?
Options
A There is an alternating current (a.c.) in the primary coil and a direct current (d.c.) in the secondary coil.
B There is a larger current in the secondary coil than in the primary coil.
C There is a changing magnetic field in the iron core.
D In the iron core there is an alternating current from the primary coil to the secondary coil.
A student uses a simple iron-cored transformer. The primary coil has 250 turns. The secondary coil has 200 turns.
The input voltage to the primary coil is .
What is the output voltage?
Options
A
B
C
D
Which device works due to electromagnetic induction?
Options
A a battery
B an electromagnet
C a motor
D a transformer
The diagram shows a generator.
What are X and Y?
Options
| X | Y | |
|---|---|---|
| A | N pole | split-ring commutator |
| B | N pole | slip rings |
| C | S pole | split-ring commutator |
| D | S pole | slip rings |
A step-down transformer changes to There are 600 turns on the primary coil.
How many turns are on the secondary coil?
Options
A 20
B 30
C 600
D 12 000
The diagram shows a transformer.
A student writes four statements about how the transformer works.
- An alternating voltage across the primary coil induces an unchanging voltage across the secondary coil.
- An alternating voltage across the primary coil produces a changing magnetic field in the iron core.
- A changing magnetic field in the iron core induces an alternating voltage across the secondary coil.
- An unchanging voltage across the primary coil produces a changing magnetic field across the secondary coil.
Which statements explain how the transformer works?
Options
A 1 and 2
B 1 and 4
C 2 and 3
D 3 and 4
A magnet moves through a coil of wire as shown.
Magnetic poles are produced at the two ends of the coil as the magnet enters and as the magnet leaves the coil.
Which pole is induced at P when the magnet enters the coil and which pole is induced at Q when the magnet leaves the coil?
Options
| pole at P when magnet enters the coil | pole at Q when magnet leaves the coil | |
|---|---|---|
| A | N | N |
| B | N | S |
| C | S | N |
| D | S | S |