1.
State what is meant by a magnetic field.
[1 mark]
- region where a magnetic force acts
JD SCIENCE
Magnetism and electromagnetism
Indicative marking points. Award marks for equivalent scientific or mathematical wording. Do not issue this sheet with the student worksheet.
2.
State what is meant by a permanent magnet.
[1 mark]
- produces its own field
3.
State what is meant by an induced magnet.
[1 mark]
- becomes magnetic in a field
4.
State what is meant by the motor effect.
[1 mark]
- a current in a field experiences a force
5.
State what is meant by Fleming's left-hand rule.
[1 mark]
- thumb motion, first finger field, second finger current
6.
State what is meant by an electromagnet.
[1 mark]
- coil with a current, often around an iron core
7.
State what is meant by electromagnetic induction.
[1 mark]
- a voltage induced when a wire cuts field lines
8.
State what is meant by a transformer.
[1 mark]
- two coils on a core, a.c. only
9.
State what is meant by the generator effect.
[1 mark]
- coil rotated in a field induces a.c.
10.
State what is meant by a solenoid.
[1 mark]
- a long coil
11.
Owain is asked about a magnetic field in a WJEC Physics paper.
(a) [2 marks]
- shown by field lines N to S
(b) [3 marks]
- stronger where lines are closer
12.
Owain is asked about a permanent magnet in a WJEC Physics paper.
(a) [2 marks]
- north and south poles
(b) [3 marks]
- attracts magnetic materials
13.
Owain is asked about an induced magnet in a WJEC Physics paper.
(a) [2 marks]
- loses magnetism when removed
(b) [3 marks]
- paperclips
14.
Owain is asked about the motor effect in a WJEC Physics paper.
(a) [2 marks]
- F = BIl
(b) [3 marks]
- Fleming's left-hand rule
15.
Owain is asked about Fleming's left-hand rule in a WJEC Physics paper.
(a) [2 marks]
- for motors
(b) [3 marks]
- 90° angles
16.
Owain is asked about an electromagnet in a WJEC Physics paper.
(a) [2 marks]
- can be switched off
(b) [3 marks]
- cranes, relays
17.
F = BIl. B=0.20 T, I=3.0 A, l=0.50 m
[3 marks]
- Final answer: 0.30 N
18.
Transformer: 200 turns to 50 turns, 12 V input. Vs
[3 marks]
- Final answer: 3 V
19.
If VpIp = VsIs, 230 V, 0.2 A primary, 12 V secondary. Is
[3 marks]
- Final answer: 3.83 A
20.
A coil has 100 turns. Turns ratio to 25 turns
[3 marks]
- Final answer: 4 : 1
21.
Force on 4 cm of wire (0.04 m), B=0.5 T, I=2 A
[3 marks]
- Final answer: 0.04 N
22.
A magnet induces 0.12 V for 0.20 s. Mean induced V is given; flux change idea — calculate V×t
[3 marks]
- Final answer: 0.024 Wb-turns (flux linkage change)
23.
Owain carries out a WJEC-style required practical linked to magnetism and electromagnetism. This is a typical WJEC required-practical style question.
(a) [2 marks]
- Independent: the independent variable for this topic
- Dependent: the measured outcome
(b) [2 marks]
- keep all other variables constant
- so the test is fair / only one variable is changed
(c) [2 marks]
- repeat and calculate a mean / use a tighter method
24.
Owain carries out collecting valid data for magnetism and electromagnetism. This is a typical WJEC required-practical style question.
(a) [2 marks]
- Independent: a chosen factor
- Dependent: a quantitative measurement
(b) [2 marks]
- calibrated instrument
- so the test is fair / only one variable is changed
(c) [2 marks]
- systematic error from zero error
25.
Owain carries out drawing a graph for magnetism and electromagnetism. This is a typical WJEC required-practical style question.
(a) [2 marks]
- Independent: x-variable
- Dependent: y-variable
(b) [2 marks]
- same scale / same apparatus
- so the test is fair / only one variable is changed
(c) [2 marks]
- not drawing a line of best fit through the trend
26.
Owain carries out evaluating a method about magnetism and electromagnetism. This is a typical WJEC required-practical style question.
(a) [2 marks]
- Independent: method change
- Dependent: precision / accuracy
(b) [2 marks]
- same sample size
- so the test is fair / only one variable is changed
(c) [2 marks]
- too few repeats
27.
Compare a magnetic field with a permanent magnet.
[4 marks]
- region where a magnetic force acts
- produces its own field
- give one linked difference
28.
Compare a permanent magnet with an induced magnet.
[4 marks]
- produces its own field
- becomes magnetic in a field
- give one linked difference
29.
Compare an induced magnet with the motor effect.
[4 marks]
- becomes magnetic in a field
- a current in a field experiences a force
- give one linked difference
30.
Compare the motor effect with Fleming's left-hand rule.
[4 marks]
- a current in a field experiences a force
- thumb motion, first finger field, second finger current
- give one linked difference
31.
Apply your knowledge of electromagnetic induction to this situation: or a field changes through a coil
[3 marks]
- or a field changes through a coil
32.
Apply your knowledge of a transformer to this situation: Vp/Vs = np/ns
[3 marks]
- Vp/Vs = np/ns