Question

Calculate the electricity bill amount for a month of 31 days, if the following devices are used as specified:
a) 3 bulbs of 30 watts for 5 hours
b) 4 tube lights of 50 watts for 8 hours
c) 1 fridge of 300 watts for 24 hours
Given the rate of electricity is 2 Rs. per unit.

Answer 1

The energy consumed by the bulbs,

As we know $enegry=power\times time$

3 bulbs $\times$ 30 watts $\times$ 5 hours $\times$ 31 days = 13950 Wh

The energy consumed by the tubes,

4 tubes $\times$ 50 watts $\times$ 8 hours $\times$ 31 days = 49600 Wh

The energy consumed by the fridge,

1 fridge $\times$ 300 watts $\times$ 24 hours $\times$ 31 days = 223200 Wh

Therefore, the total energy consumption is given by,

13950+49600+223200 = 286750 Wh = 286.75 KWh

We need to convert it into units, where 1 unit = 1 kWh

So, electricity bill = 286.75 units $\times$ 2 rs = Rs. 573.5