Question

An electric refrigerator rated $600W$ operates $8\text{ hours a day}$. What is the cost of the energy to operate it for $30\text{ days}$ at $Rs4.00$ per $kWh$?

Answer 1

Hint: First of all the power of the refrigerator should be converted into kilowatt. Then find out the total operation hour. The total Work-done or energy should be calculated by taking the product of the operational time and power in kilowatts. Then find out the total cost of energy also. These all may help you to solve this question.

Complete step-by-step solution:
The power of the electric refrigerator can be written as,
$P=600W$
Let us convert this into the units of kilowatts,
$P=600W=0.6kW$
As it is mentioned that we have to calculate the total energy in $30\text{ days}$ the total operational hour of the electrical refrigerator can be given as,
$T=8\times 30=240h$
Work-done or the total electrical energy can be found as,
$W=0.6\times 240=144kWh$
As per the question, it is given that for $1kWh$ there is a charge of rupees $4$,
Therefore the total cost of energy in order to operate for this much days,
$\text{cost=}144\times 4=Rs.576$
Hence the answer to the question has been obtained.

Note: Energy is the work performed per unit time and power is given as the time rate of variation of energy. Energy is usually determined in joules or watt-seconds. However, the power is determined in watts, or in joules per second. The higher the power is, the faster the stored energy in a battery. Kilowatt-hour is the energy that is equivalent to a thousand watts of power in a one-hour time period. It is the practical unit used in our daily life. The electrical energy in our daily household is measured using this unit.