In a house three bulbs of 100w each are lighted for 4 hours daily and six tube lights of 20 W each are lighted for 5 hours daily and a refrigerator of 400 W is worked for 10 hours daily for a month of 30 days. Calculate the electricity bill if the cost of one unit is Rs 4.00

Explanation

No. of bulbs in a house, N = 3
Rated power on each bulb, P = 100 W
Time of lighted t = 4 H
Energy consumption of 3 bulbs per day `= (Npt)/(1000)` KWH
Energy consumption of 3 bulbs for 30 days `= (30 N P t)/(1000)` KWH
`E_(B) = (30 xx 3 xx 100 xx 4)/(1000) = 36 KWH`
Similarly, energy consumption of 6 tube lights
for 30 days, `E_(T) = (30 xx 6 xx 20 xx 5)/(1000) KWH = 18 KWH`
And similarly, Energy consumption of one Refrigerator for 30 days
`E_(R ) = (30 xx 400 xx 10)/(1000) KWH = 120 KWH`
`:.` The total energy consumption, `E = E_(B) + E_(T) + E_(R ) = (36 + 18 + 120)` KWH
Cost of 1 unit = Rs. 4.00/
Cost of 174 unit = No. of units `xx` cos of 1 unit
`= 174 xx 4 = Rs. 696 /-`
`:.` Electricity bill for one month of that house = Rs. 696 .-