Question

part a
estimate the resistance of the 120 - vrms circuits in your house as seen by the power company, when everything electrical is unplugged.
the resistance is zero.
the resistance is infinite.
there is not enough information to answer.
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part b
estimate the resistance of the 120 - vrms circuits in your house as seen by the power company, when there are two 60 w lightbulbs burning.
express your answer to two significant figures and include the appropriate units.
r = 120 ω

Explanation:

Step1: Determine the formula for power

The formula for power in an electrical circuit is \(P=\frac{V^{2}}{R}\), where \(P\) is power, \(V\) is voltage, and \(R\) is resistance. We can rearrange this formula to solve for \(R\): \(R = \frac{V^{2}}{P}\).

Step2: Calculate the total power

There are two \(60\space W\) light - bulbs burning. So the total power \(P=60 + 60=120\space W\). The voltage \(V = 120\space V_{rms}\).

Step3: Substitute values into the formula

Substitute \(V = 120\space V\) and \(P=120\space W\) into \(R=\frac{V^{2}}{P}\). We get \(R=\frac{(120)^{2}}{120}\).

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Answer:

\(R = 120\space\Omega\)