JAMB and WAEC Physics questions: Electromagnetic induction

25 questions with answers and explanations. Tap an option to check yourself.

1. Question 21· Electromagnetic induction· JAMB

   A transformer works on the principle of

   • Amutual induction
   • Bself-induction only
   • Cthe heating effect of current
   • Delectrolysis

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   Explanation and discussion

2. Question 22· Electromagnetic induction· JAMB

   Electric power is transmitted over long distances at very high voltage mainly to

   • Amake the cables lighter
   • Bincrease the current
   • Creduce energy lost as heat in the cables
   • Dincrease the frequency

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   Explanation and discussion

3. Question 23· Electromagnetic induction· JAMB

   A transformer steps 240 V down to 12 V. If the secondary coil has 50 turns, the primary has

   • A2.5 turns
   • B1,000 turns
   • C20 turns
   • D50 turns

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   Explanation and discussion

4. Question 24· Electromagnetic induction· WAEC

   A transformer has 200 turns in its primary and 1000 turns in its secondary. If 12 V a.c. is applied, find the output voltage.

   • A60 V
   • B2.4 V
   • C12 V
   • D240 V

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   Explanation and discussion

5. Question 25· Electromagnetic induction· WAEC

   A transformer works only with alternating current because

   • Ad.c. damages the core
   • Bd.c. is too strong
   • Ca.c. has no voltage
   • Dit needs a changing magnetic flux

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   Explanation and discussion