A charge of $18$ $18$ $C$ $C$ passes through a circuit every $4$ $4$ $s$ $s$ . If the circuit can generate $36$ $36$ $W$ $W$ of power, what is the circuit's resistance?

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Answer 1 · 2017-06-24T13:37:52

$R = \frac{P}{I^{2}} = 1.78$ $R=P/I^2=1.78$ $\Omega$

We know that the current $I$ in a circuit where a charge $Q$ passes every $t$ seconds is given by:

$I=Q/t=18/4=4.5$ $A$

We also know power in a circuit in which a current $I$ is flowing through a resistance $R$ is given by:

$P=I^2R$

Rearranging:

$R=P/I^2=36/(4.5^2)=1.78$ $\Omega$

A charge of 181818 CCC passes through a circuit every 444 sss. If the circuit can generate 363636 WW W of power, what is the circuit's resistance?