Question

Calculate the cost of operating a heater of 500w for 20 hours at rate of Rs. 3.90 per unit?

Answer 1

Hey!!
Power = 500W
we know that energy consumed = P×(total time )

=> E = 500×20 = 10000 W-h
or 10 kWh
or 10 units

Now 1 unit = 3 .90 Rs
thus 10 units will cost 3.90×10 => 39 Rs

Answer 2

Energy = Power × Time
= 500 Watt × 20 hour
= 10 kWh

As a convention 1 KWh is considered as 1 unit

So, cost = 10 unit × ₹3.90 1/unit & ₹39

Cost of operating heater is ₹39.0