Question

A refrigerator having a power rating of 350W operates for 10 hours a day. Calculate the cost of electrical energy to operate if for a month of 30 days. The rate of electrical energy is Rs. 340 per kWh.

Answer 1

Electrical energy, `E = P xx t`
Power, `P = 350 W`
`= (350)/(1000) kW`
`= 0.35 kW`
And, Time, `t = 10 xx 30` hours
`= 300 h`
Now, putting these values of P and t in the formula,
`E = P xx t`
We get: `E = 0.35 xx 300 kWh`
`= 105 kWh`
Thus, the electrical energy consumed by the refrigerator in a month of 30 days is 105 kilowatt-hours.
Now, Cost of 1 kWh of electricity = Rs. 3.40
So, Cost of 105 kWh of electricity = Rs. `3.40 xx 105`
= Rs. 357`