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pious&peevish
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Homework Statement
A power supply with ΔVrms = 111 V is connected between points a and d in the figure below. (It's attached to the thread, but the basic idea is that this is an RLC circuit connected in series).
As shown, R = 39.5 Ω, L = 157 mH and C = 73.2 μF. At what frequency will it deliver a power of 210 W? Enter one of the two possible frequencies (in Hz).
Homework Equations
See Part 3 below
The Attempt at a Solution
We are given that P=I(rms)*V(rms), and by substituting in the values given in the problem we have 210 W = I(rms)*(111 V). Therefore our expected value for I(rms) should be 1.892 A.
I(rms)=V(rms)/Z, so 1.892 A = (111 V)/Z and the expected value for Z is 58.67 ohms.
58.67 ohms = √((39.5^2)+((2*pi*f*0.157 H)-(1/(2*pi*f*(73.2*(10^-6) F))^2).
From here, I solved for f, but the value I got was incorrect. I must have missed something somewhere, but I can't see what it is...