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Q23 (CISF/2020) Science & Technology › Basic Science (Physics, Chemistry, Biology)

An electric refrigerator rated 400 W operates 10 hours/day. What is the cost of the energy to operate it for 30 days at ₹ 3.00 per kWh ?

Result
Your answer: —  Â·  Correct: A

Explanation

To calculate the total cost, we first determine the total energy consumed in kilowatt-hours (kWh):

  • Power of the refrigerator: 400 W = 400/1000 kW = 0.4 kW.
  • Total operating time: 10 hours/day × 30 days = 300 hours.
  • Total energy consumed: Energy = Power × Time = 0.4 kW × 300 hours = 120 kWh.

Now, we calculate the cost based on the given rate:

  • Cost: Total Energy × Rate per kWh = 120 kWh × ₹ 3.00/kWh = ₹ 360.

Thus, the cost of the energy to operate the refrigerator for 30 days is ₹ 360.

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