Question

An electric room heater has a resistance of 20Ω and operates at 220V for 5 minutes. Calculate the heat energy dissipated by it in kilojoules.

Answer 1

$\huge\text{\underline{Answer}}$

Resistance of heater = 20 Ω

Voltage = 220 V

Time = 5min = 300 second

Heat energy dissipiated is given by

$\boxed{H = \frac{ {V}^{2} }{r} \times t}$

putting the value of V,r and t.

$\implies$ $\bold{H = \frac{220 \times 220}{20} \times 300}$

$\implies$ $\bold{H =726000j }$

$\implies$ $\bold{H = 726 Kj }$

The heat energy dissipiated is $\bold{726 Kj }$