Current

Consider an electric space heater is built with a 40 ohm resistor. How much current (amps) is needed to produce 500 W of heat?

Expand Hint
Power absorbed by a resistive element:
$$$P=VI=\frac{V^{2}}{R}=I^2R$$$
where $$V$$ is voltage, $$I$$ is current, and $$R$$ is resistance.
Hint 2
Based on the problem statement’s givens, solve for current using the equation:
$$$P=I^2R$$$
Power absorbed by a resistive element:
$$$P=VI=\frac{V^{2}}{R}=I^2R$$$
where $$V$$ is voltage, $$I$$ is current, and $$R$$ is resistance.

Solving for Current using the problem statement’s knowns:
$$$P=I^2R\to 500W=I^2(40\Omega)$$$
$$$I=\sqrt{\frac{500W}{40\Omega}}=3.5\:A$$$
3.5 A