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JAMB Physics 1982 Question 38

Question 38

Current Electricity

A high-resistance voltmeter reads 3.0 V when connected across the terminals of a battery on open circuit and 2.6 V when the battery supplies a current of 0.2 A through a lamp. The resistance of lamp is

  1. A.2.00 Ω
  2. B.13.00 Ω
  3. C.0.52 Ω
  4. D.0.13 Ω
  5. E.1.50 Ω
Show the answer and explanation

Answer: B (13.00 Ω)

Explanation

The terminal p.d. across the lamp is 2.6 V with 0.2 A flowing, so R = 2.6/0.2 = 13 Ω.