Question

An electric heater draws a current of 10A from a 220V supply. What is the cost of using the heater for 5 hours everyday for 30 days if the cost of 1 unit (1 kWh) is Rs 5.20?

Answer 1

In this problem, first of all we have to calculate the power of the heater by using the given values of current and voltage. This can be done by using the formula:
`P = V xx l`
Here, Voltage (or p.d), `V = 220V`
And, Current, `I = 10A`
So, Power, `P = 220 xx 10W`
`= 2200W`
`= (2200)/(1000) kW`
`= 2.2 kW` ....(1)
Now, Electric energy consumed, `E = P xx t`
Here, Power, `P = 2.2 kW`
And, Time, `t = 5h`
So, Electric energy consumed in 1 day `= 2.2 xx 5`
`= 11 kWh`
And, Electric energy consumed in 30 days `= 11 xx 30`
`= 330 kWh` (or 330 units) ....(2)
Now, Cost of 1 unit of electricity = Rs 5.20
So, Cost of 330 unit of electricity = Rs `5.20 xx 330`
= Rs 1716
Before we go further and discuss the heating effect of electric currnet, please answer the following questions: