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JAMB Physics 1994 Question 45

Question 45

Current Electricity

In the circuit diagram above, calculate the current in the 12 Ω resistor if the cell has an e.m.f. of 12V and an internal resistance of 1Ω.

Diagram for this question
  1. A.0.8A
  2. B.1.0A
  3. C.1.6A
  4. D.2.4 A
Show the answer and explanation

Answer: A (0.8A)

Explanation

12 Ω and 6 Ω in parallel give 4 Ω; with the 1 Ω internal resistance the total is 5 Ω, so the cell gives 12/5 = 2.4 A. The 12 Ω branch takes 6/(12 + 6) of this: 0.8 A.