Electromagnetic induction is the production of an e.m.f. when a conductor cuts magnetic field lines, and Faraday's law ties that e.m.f. to flux linkage change, so this IB sheet opens from the cutting-motion picture. Moving the magnet faster raises the induced e.m.f. in the answers.
Key Takeaways
Induction is the production of an e.m.f. when a conductor cuts field lines (Q1).
Induced e.m.f. is proportional to the rate of change of flux linkage (Q2).
Moving the magnet faster increases the induced e.m.f. (Q4).
Section A: Multiple Choice Questions (1 Mark Each)
Choose the correct option for each question.
1.Electromagnetic induction is the production of
(a) an e.m.f. when a conductor cuts magnetic field lines(b) static charge(c) a permanent magnetic field(d) a permanent magnet
2.Faraday's law states that the induced e.m.f. is proportional to
(a) the rate of change of magnetic flux linkage(b) the magnetic field strength only(c) the current in the coil(d) the temperature
3.Lenz's law states that the induced current opposes
(a) the change producing it(b) the voltage(c) gravity(d) the magnetic field direction only
4.The induced e.m.f. can be increased by
(a) moving the magnet faster(b) moving the magnet slower(c) using a weaker magnet(d) removing the coil
5.A transformer works on the principle of
(a) electromagnetic induction(b) static electricity(c) chemical action(d) thermal expansion
6.A step-up transformer
(a) increases the voltage(b) decreases the voltage(c) converts d.c. into a.c.(d) increases the power
Section B: Short Answer Type Questions (2 Marks Each)
Show all steps clearly.
7.Define electromagnetic induction.
8.State Faraday's law.
9.State Lenz's law.
10.Give two ways to increase the induced e.m.f. in a coil.
11.Why does a transformer not work with direct current (d.c.)?
12.What is magnetic flux linkage?
13.A transformer steps 230 V up to 460 V. What is the turns ratio?
14.Give one use of a step-down transformer.
Section C: Numericals & Word Problems (3 Marks Each)
Apply the concepts to solve the problems. Show all working.
15.A transformer has 500 primary turns and 1000 secondary turns with a 200 V primary supply. Using Vp ÷ Vs = Np ÷ Ns, find the secondary voltage.
16.A transformer has 800 primary turns and 200 secondary turns with a 240 V primary supply. Find the secondary voltage.
17.A coil of 200 turns has a magnetic flux change of 0.05 Wb in 0.5 s. Using E = N × ΔΦ ÷ Δt, find the induced e.m.f.
18.A transformer steps 12 V up to 240 V. Using Np ÷ Ns = Vp ÷ Vs, find the turns ratio.
19.A coil of 100 turns has a magnetic flux change of 0.02 Wb in 0.4 s. Using E = N × ΔΦ ÷ Δt, find the induced e.m.f.
20.An ideal transformer has a 200 V primary supply and a 1000 V secondary supply. Using Vp ÷ Vs = Np ÷ Ns, find the turns ratio.
Answer Key
1. a) an e.m.f. when a conductor cuts magnetic field lines
2. a) the rate of change of magnetic flux linkage
3. a) the change producing it
4. a) moving the magnet faster
5. a) electromagnetic induction
6. a) increases the voltage
7. Refer to solution guide.
8. Refer to solution guide.
9. Refer to solution guide.
10. Refer to solution guide.
11. Refer to solution guide.
12. Refer to solution guide.
13. Refer to solution guide.
14. Refer to solution guide.
15. Refer to solution guide.
16. Refer to solution guide.
17. Refer to solution guide.
18. Refer to solution guide.
19. Refer to solution guide.
20. Refer to solution guide.
End of Worksheet
People Also Ask
What is electromagnetic induction?
The production of an e.m.f. when a conductor cuts magnetic field lines, option (a) in this worksheet (Q1).
What is induced e.m.f. proportional to?
The rate of change of magnetic flux linkage, option (a) in this worksheet (Q2).
How can the induced e.m.f. be increased?
Move the magnet faster, option (a) in this worksheet (Q4).
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