Question

Calculate the monthly bill for a heater of resistance 50 Ω, which is used on 200 V mains, such that its daily use is for 4 h. The energy cost is ₹ 2.50 per kWh.

Answer 1

Power of heater P = $$\frac{V^2}{R}$$

$$= \frac{(200)^2}{50}$$

= 800 W

∴ Energy consumed by the heater in a day = P × t

= 800 W × 4 h

= 3200 Wh

∴ Energy consumed by the heater in 30 days (month) = 3200 Wh × 30

= 96000 Wh

= 96 kWh

∴ Monthly bill \[=96 \mathrm{kWh} \times \frac{₹ 2.5}{\mathrm{kWh}}\] = ₹ 240