Question

Calculate the electricity bill of a house which has 5 bulbs of 60watt each, 4fans of 80watt each, 2 tube lights of 9watt each, one cooler of 140 watt and one geyser of 850watt. These appliances are used for 5hours daily and the bill to be generated for the month of October. Take the cost of 1 unit of electricity as Rs. 2.40.

Answer 1

Hint : As a first step, write down the given data carefully. Then you could find the power consumed for 5 hours by each of the appliances and then take their sum to get the net power consumption per day. Then multiply this value by 31 days of October. After that find the equivalent electricity units and multiply this by Rs.2.40 to get the bill generated.

Formula used:
1 unit of electricity = 1000watt-hour

Complete step-by-step solution:
Let us first find the total energy consumed per day.
The 5 bulbs for 5 hours consume;
$\left( 5\times 60 \right)watt\times 5h=1500watth$
The 4 fans for 5hours consume;
$\left( 4\times 80 \right)\times 5=1600watth$
The 2 tube lights for 5 hours consume;
$\left( 2\times 9 \right)watt\times 5h=90watth$
$\left( 1\times 140 \right)\times 5=700watth$
One cooler for 5 hours,
$\left( 1\times 859 \right)\times 5=4250watth$
Now the total energy consumed by all these appliances would be their sum,
$1500+1600+90+700+4250=8140watth$
Now we know that 1 unit of current is equivalent to 1000watt-hour, so, the above total energy consumed would be equivalent to,
$\dfrac{8140watth}{1000}=8.140units$
In the month of October we have 31 days, and the unit of electricity for that month would be,
$8.140\times 31=252.34units$
And we have the cost of 1 unit of electricity given as Rs. 2.40, so bill for the month of October would be,
$252.34units\times Rs.2.40=Rs.605.616$
The bill generated for the month of October for the given power consumption is Rs. 605.616.

Note: The ones who have seen the electricity bill for our home, etc, may be familiar that power consumed is given as ‘units’. So, as a physics student one should know that this 1unit of electricity is equivalent to 1kWh of electrical consumption in units of electrical power.