Question 86
An electric heater is rated at 2 kW. Electrical energy costs Rs.4 per kWh. What is the cost of using the heater for 3 hours?
Solution
$$ power = \frac{work}{time} $$
given power = 2 kW
time = 3 hours
substituting
$$ 2 kW = \frac{work}{3} $$
solving work = 6
Electrical energy costs Rs.4 per kWh
cost of using the heater for 3 hours = $$ 6 \times 4 = Rs 24 $$
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