Question

An electric heater of resistance 8 ohms draws 15 A from the service mains for 2 hours. Calculate the rate at which heat is developed in the heater. (Give your answer in $\frac{J}{s}$)

• A. 1800
• B. 1600
• C. 500
• D. 800

Answer 1

The correct option is A

1800

Here, I = 15 A, R = 8 W, t = 2 hr

Rate at which heat is developed, i.e, electric power, P = $I^2$ R = (${15}^2$) $\times$ 8 = 1800 W = 1800 $\frac{J}{s}$