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JAMB Physics 2001 Question 28

Question 28

Electrical Energy and Power

The cost of running five 60 W lamps and four 100 W lamps for 20 hours if electrical energy costs N10.00 per kWh is

  1. A.N280.00
  2. B.N160.00
  3. C.N120.00
  4. D.N140.00
Show the answer and explanation

Answer: D (N140.00)

Explanation

Total power = 5 × 60 + 4 × 100 = 700 W = 0.7 kW. Energy = 0.7 × 20 = 14 kWh, costing 14 × N10 = N140.00.