CBSE Class 10 Answered

Energy = Power x Time

For example, if a 75 W bulb (power) is turned on for 2 hours (time), it will use 150 Wh or 0.15 kWh of energy .

The cost for each unit of energy we use is measured in Rupees (Indian) per kWh.

The typical cost per unit of energy is Rs.10/kWh.

Using the equation below, we can determine the cost of our energy use:

Cost of energy use = Energy used x Cost per unit of energy:

Using our example above, the cost of using a 75 W bulb for 2 hours is:

Cost of energy use = 0.15 kWh x 10 Rs./kWh = Rs. 1.5