A current-carrying wire in a magnetic field feels a force called the motor effect, and Fleming's left-hand rule finds its direction, so this Year 9 sheet opens with the two motor ideas. The key adds a transformer answer and that faster flux change makes more e.m.f.
Key Takeaways
The force on a current-carrying wire in a magnetic field is the motor effect (Q1).
Fleming's left-hand rule gives the direction of force on a current-carrying wire (Q2).
Q4 records a transformer answer.
Section A: Multiple Choice Questions (1 Mark Each)
Choose the correct option for each question.
1.A current-carrying wire placed in a magnetic field experiences a force. What is this effect called?
(a) the motor effect(b) the dynamo effect(c) electromagnetic induction(d) static attraction
2.Fleming's left-hand rule is used to find the direction of what?
(a) the force on a current-carrying wire in a magnetic field(b) the induced current in a generator(c) magnetic field lines(d) an electric field
3.Moving a magnet into a coil of wire induces what?
(a) an electromotive force (e.m.f.)(b) a permanent magnetic pole(c) a current with no e.m.f.(d) no effect at all
4.Which device uses electromagnetic induction to transfer energy?
(a) transformer(b) battery(c) electric heater(d) resistor
5.The induced e.m.f. in a coil becomes larger when the magnet is moved how?
(a) faster(b) slower(c) and then stopped(d) very slowly
6.A generator converts which types of energy?
(a) kinetic energy into electrical energy(b) electrical energy into kinetic energy(c) chemical energy into light(d) heat into sound
Section B: Short Answer Type Questions (2 Marks Each)
Show all steps clearly.
7.State the motor effect.
8.State what is meant by electromagnetic induction.
9.Give two ways to increase the size of the induced e.m.f. in a coil.
10.State Fleming's left-hand rule.
11.What is the function of a generator?
12.What is the function of a transformer?
13.What is the difference between alternating current (a.c.) and direct current (d.c.)?
14.Why does moving a magnet into a coil produce a current in the coil?
Section C: Numericals & Word Problems (3 Marks Each)
Apply the concepts to solve the problems. Show all working.
15.A transformer has 1000 turns on the primary coil and 250 turns on the secondary coil. The primary is supplied with 230 V. Using Vp ÷ Vs = Np ÷ Ns, calculate the secondary voltage.
16.A transformer has 2000 primary turns and produces 25 V from a 100 V primary supply. Using Np ÷ Ns = Vp ÷ Vs, calculate the number of secondary turns.
17.A wire of length 0.5 m carrying a current of 4 A is placed at right angles to a magnetic field of flux density 0.5 T. Using F = B × I × L, calculate the force on the wire.
18.A current of 5 A flows in a 0.3 m length of wire placed at right angles to a field of flux density 0.2 T. Using F = B × I × L, calculate the force.
19.An ideal transformer has a 240 V primary supply and a 24 V secondary supply. If the primary coil has 500 turns, use Vp ÷ Vs = Np ÷ Ns to find the number of secondary turns.
20.An ideal transformer supplies 100 W of power at 20 V to a device. Using P = V × I, calculate the current in the device.
Answer Key
1. a) the motor effect
2. a) the force on a current-carrying wire in a magnetic field
3. a) an electromotive force (e.m.f.)
4. a) transformer
5. a) faster
6. a) kinetic energy into electrical energy
7. Refer to solution guide.
8. Refer to solution guide.
9. Refer to solution guide.
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11. Refer to solution guide.
12. Refer to solution guide.
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15. Refer to solution guide.
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19. Refer to solution guide.
20. Refer to solution guide.
End of Worksheet
People Also Ask
What is the force on a current-carrying wire in a magnetic field called?
The motor effect, option (a) in this worksheet (Q1).
What does Fleming's left-hand rule find?
The force on a current-carrying wire in a magnetic field, option (a) in this worksheet (Q2).
What device is recorded in Q4?
A transformer.
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