# Power Dissipated By Resistor is LRC Circuit

[Note by mentor: this post does not use the homework template because it was originally posted in a non-homework forum.]

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Problem:
What is the average power dissipated by a 25-Ω resistor in an LRC series ac circuit for which the power factor is equal to 0.25 and the maximum voltage of the ac source is 8.0 V?

Attempt at Solution:
We know that Pav = (1/2)(V)(I)cos(phi) where cos(phi) is the power factor. So if we substitute I for V/I (ohms law) we get Pav = (1.2)((V^2)/R)cos(phi). Plugging in all the values I get that Pav = .32W which is clearly incorrect...

What did I do wrong?

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[Note by mentor: this post does not use the homework template because it was originally posted in a non-homework forum.]

---------------------------------------------

Problem:
What is the average power dissipated by a 25-Ω resistor in an LRC series ac circuit for which the power factor is equal to 0.25 and the maximum voltage of the ac source is 8.0 V?

Attempt at Solution:
We know that Pav = (1/2)(V)(I)cos(phi) where cos(phi) is the power factor. So if we substitute I for V/I (ohms law) we get Pav = (1.2)((V^2)/R)cos(phi). Plugging in all the values I get that Pav = .32W which is clearly incorrect...

What did I do wrong?