Question

(iii) A refrigerator of 200 W is operated for 10 hours per day. Find out the cost of energy to operate it for 30 days at the rate of ₹6 per kWh.

Hint:

To find the energy cost, use the formula: \(\text{Cost} = \text{Power (kW)} \times \text{Time (hours)} \times \text{Rate (₹/kWh)}\).

Answer 1

To calculate the cost of energy used by the refrigerator, we first need to find the total energy consumed in kilowatt-hours (kWh). 1. Power of refrigerator = 200 W = 0.2 kW (since 1000 W = 1 kW).
2. Time of operation per day = 10 hours.
3. Total time of operation for 30 days = \( 10 \times 30 = 300 \, \text{hours} \). Now, the total energy consumed by the refrigerator is: \[ \text{Energy consumed (in kWh)} = \text{Power} \times \text{Time} = 0.2 \, \text{kW} \times 300 \, \text{hours} = 60 \, \text{kWh} \] The cost of energy is calculated as: \[ \text{Cost} = \text{Energy consumed} \times \text{Rate} = 60 \, \text{kWh} \times 6 \, \text{₹/kWh} = 360 \, \text{₹} \] Thus, the cost of operating the refrigerator for 30 days is ₹360.