Question

in a factory an electric bulb of 500W is used for 2hrs and an electric motor of 0.5 horsepower is used for 5 hrs everyday. calculate the cost of using bulb and the motor for 30 days if the electrical energy is three rupees per unit.

Answer 1

here,

the total energy used by 500W electric bulb

E_bulb = 500W x 2hrs x 30days = 30000 Wh = 30kWh

and

the total energy used by 0.5 hp (= 373W) motor

E_motor = 373 x 5hrs x 30days = 55950 Wh = 55.95kWh

so,

total energy consumed

E = E_bulb + E_motor = 30kWh + 55.95kWh = 85.95kWh

so,

total electricity cost will be

total cost = 85.95kWh x 3/kWh

so,

total cost = Rs. 257.85