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JAMB Physics 2008 Question 40

Question 40

Current Electricity

An electric generator has an e.m.f. of 240 V and an internal resistance of 1 Ω. If the current supplied by the generator is 20 A when the terminal voltage is 220 V, find the ratio of the power supplied to the power dissipated.

  1. A.11:1.
  2. B.1:11
  3. C.12:11.
  4. D.11:12.
Show the answer and explanation

Answer: C (12:11.)

Explanation

Power supplied by the generator = EI = 240 × 20; power delivered to the external circuit = VI = 220 × 20. Ratio = 240 : 220 = 12 : 11.