# A charge of 40 C passes through a circuit every 8 s. If the circuit can generate 5 W of power, what is the circuit's resistance?

Jul 23, 2016

I found: $0.2 \Omega$

#### Explanation:

With charge and time you can find current as:
$I = \frac{Q}{t} = \frac{40}{8} = 5 A$
Using the definition of power and Ohm's Law you get:
$P = V I$
and
$V = R I$
so combining the two:
$P = {I}^{2} R$
and rearranging:
$R = \frac{P}{I} ^ 2 = \frac{5}{5} ^ 2 = \frac{1}{5} = 0.2 \Omega$