Q. A house wife uses a 100 W bulb 8 h a day , and an electric heater of 300 W for 4 h a day. The total cost for the month of June at the rate of 0.05 rupee per unit will be
A) Rs 20
B) Rs 25
C) Rs 30
D) Rs 30 paise 50
Explanation
(c) Since the unit of electrical energy is kilowatt hour (kWh),
So total number of units consumed is
$N = (0.1 \times 8 + 0.3 \times 4) \times 30$
(Because June has 30 days)
$\therefore N = 60\ units$
Total cost $= 60 \times 0.5 = 30$ Rs.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.