Question

A $1kW$ heater is meant to operate at $200V$. How much power (in watt) will it consume if the line voltage drops to $100V$?

Answer 1

$P=\frac{V^2}{R}$

where,

$P\to Power$

$V\to Voltage$

$R\to Resistance$

Resistance of the heater,

$R=\frac{V^2}{P}=\frac{{200}^2}{1000}=40\Omega$

Power consumed if the voltage drops to 100V,

$P=\frac{V^2}{R}=\frac{{100}^2}{40}=250W$