Question

An electric refrigerator rated 400w operates 8hour/day . What is its cost of energy to operate it for 30 days at Rs3.00 per kWh? Express this amount of energy in its S.I unit.

Answer 1

Here,Power P=400 W=400/1000 kW=0.40 kW

Time t=8 x 30=240 hours

Now electrical energy is given by,

E=P x t

=0.40 x 240=96 kWh

Thus the electric energy consumed by the refrigerator in a month of 30 days is 96 kWh.

Cost of 96 kWh of electricity=96 x 3= Rs. 288

Answer 2

total electric used by refrigerator  =  96 kwh
cost  of 1khw electric  =3
total cost           = 3*96
                          = Rs .288     ans...