If a current of $4 A$ $4 A$ passing through a circuit generates $42 W$ $42 W$ of power, what is the resistance of the circuit?

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Answer 1 · 2016-04-24T16:15:52

$approx2.6Omega$

Power is current times voltage,

$P=IV$

Substituting in the power is $42W$ and current is $4A$ from the question,

$42=4*V$
$V=10.5$

A second equation tells us that voltage is current times resistance, so

$V=IR$ .

Putting in the values of $V=10.5V$ and $I=4A$ and rearranging to make $R$ the subject,

$R=10.5/4=2.625Omegaapprox2.6Omega$

You could put the two equations together and say that

$R=P/I^2$

and simply solve straightaway.

If a current of 4 A4A4 A passing through a circuit generates 42 W42W42 W of power, what is the resistance of the circuit?