 # If a current of 8A passing through a circuit generates Ashley Fritz 2022-05-10 Answered
If a current of 8A passing through a circuit generates 14W of power, what is the resistance of the circuit?
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I would combine two laws I have memorised here: Ohm's Law,
V=IR
and the Power Law
P=VI
I have a current, I, of 8 A (ampere) and a power, P, of 14W (watt). i have been asked for a resistance, $R\mathrm{\Omega }$ (ohm).
So I want a formula that includes only those three things. If I want to get rid of the V in the Power Law, I can replace it with what Ohm's Law says is equal to V=IR.
So
$P=\left(IR\right)\ast I={I}^{2}\ast R$
I need to rearrange to make R the subject, so I divide both sides by ${I}^{2}$ and swap the sides:
$R=\frac{P}{{I}^{2}}=\frac{14}{{8}^{2}}=\frac{14}{64}=0.22\mathrm{\Omega }$ (rounded to two decimal places).