Question

two electric bulbs rated 60 w and 40 w respectively are used 5 hours per day for 20 days if the cost of unit is rupees 4.00 and find the cost of energy used

Answer 1

Energy is equal to power×time

Bulb 1

Energy=60w×5hrs×20=6000watt hour

So 6000/1000 kWh=6kwh is the energy used

So cost for bulb 1 = 6×4=24 rupees

Bulb 2

Energy=40w×5×20=4000wh

Energy=4kwh

Cost =4×4=16 rupees