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JAMB Physics 1982 Question 30

Question 30

Current Electricity

The value of the series resistance required to convert the above galvanometer (Fig. 9) into a voltmeter with a full range deflection of 15 V is

Diagram for this question
  1. A.985 ohms
  2. B.990 ohms
  3. C.995 ohms
  4. D.1,000 ohms
  5. E.1,005 ohms
Show the answer and explanation

Answer: C (995 ohms)

Explanation

At full scale 0.015 A flows through 5 Ω plus R: 0.015 × (5 + R) = 15, so 5 + R = 1000 and R = 995 Ω.