Electromagnetic Induction
Physics · 50 practice questions
Faraday's laws of electromagnetic induction; factors affecting induced e.m.f.; Lenz's law as an illustration of conservation of energy; a.c. and d.c. generators; transformers; the induction coil; inductance — explanation, unit, energy stored in an inductor, applications/uses; eddy current — reduction and applications.
- Interpret the laws of electromagnetic induction and identify factors affecting induced e.m.f.
- Recognize how Lenz's law illustrates conservation of energy.
- Examine the principles of operation of generators, transformers and the induction coil.
- Calculate effective inductance and the energy stored in an inductor.
- Describe how eddy current losses can be reduced and how eddy currents can be used.
Try a few questions
- Practice question 1
A coil experiences a flux change from 0.02Wb to 0.08Wb over 0.3 seconds. The induced e.m.f. is
- A.0.06 V
- B.0.2 V
- C.0.3 V
- D.2 V
Show the answer
B. 0.2 V
Induced e.m.f. = ΔΦ/Δt = (0.08-0.02)/0.3 = 0.06/0.3 = 0.2 V.
- Practice question 2
For the transformer above (240V primary, 60V secondary), if the secondary current is 8A, the primary current (assuming 100% efficiency) is
- A.2 A
- B.32 A
- C.8 A
- D.0.5 A
Show the answer
A. 2 A
Primary current = (secondary voltage x secondary current) ÷ primary voltage = (60x8)/240 = 480/240 = 2 A.
- Practice question 3
Wireless charging pads for smartphones use electromagnetic induction between a coil in the pad and a coil in the phone to
- A.transfer electrical energy only through a direct, wired connection
- B.transfer electrical energy without a direct physical connection
- C.generate light energy for the phone's display
- D.permanently store data within the smartphone's coil
Show the answer
B. transfer electrical energy without a direct physical connection
This coil-to-coil induction, requiring only close proximity rather than a physical plug, is the basis of wireless charging technology.
More UTME Physics topics
Practise with instant feedback
Answer questions one at a time and see the right answer and the reason straight away. Free to start.
Start practising