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JAMB Physics 1985 Question 40

Question 40

Current Electricity

Which of the graphs A − E (Fig. 3) represents the current-voltage (I − V) relationship for a cell with internal resistance?

Diagram for this question
  1. A.A
  2. B.B
  3. C.C
  4. D.D
  5. E.E
Show the answer and explanation

Answer: C (C)

Explanation

For a cell, V = E − Ir: the more current it supplies, the lower its terminal voltage. So I falls in a straight line as V rises, reaching zero when V equals the e.m.f., as in graph C.