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JAMB Physics 2009 Objective — Question 40

Question 40 of 50 from the Joint Admissions and Matriculation Board (JAMB) Physics 2009 Objective paper, with the correct answer and a full explanation.

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

  • A. 11:1Correct
  • B. 1:11
  • C. 11:12
  • D. 12:11

Explanation

Power generated = IV(e.m.f) = 20x240 = 4800W. Power supplied = IV(terminal) = 20x220 = 4400W. Power dissipated = 4800-4400 = 400W. Ratio supplied:dissipated = 4400:400 = 11:1.

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