Electromagnetic Induction in AC circuits

AI Thread Summary
In the discussion on electromagnetic induction in AC circuits, participants analyze a series circuit containing a resistor, capacitor, and inductor connected to a 120 V (rms) source. The maximum current occurs at a specific frequency determined by the formula f = 1 / (2π√(LC)), but users struggle to calculate the correct frequency. The maximum rms current is found using the formula Irms = Vrms / XC, where XC is the capacitive reactance. When replacing the capacitor with a larger value, the new rms current is recalculated using the same principles. The conversation highlights confusion about the calculations and the relevance of reactance in determining current.
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A 9.7 Ω resistor, a 10.8 µF capacitor, and a 27.9 mH inductor are connected in series with a 120 V (rms) source with variable frequency.
(a) At what frequency will the current be maximum?

Hz



(b) Find the maximum rms current.

A



(c) Suppose you now replace the 10.8 µF capacitor by a 22.0 µF capacitor. What is the new value of the rms current?

A





a ) frequency f = 1 / 2π √ L C
= 1/ 2π √27.9 mH * 10.8μF
= _____ Hz cannot get right frequency
b ) Maximum rms current Irms = Vrms / XC
XC = 1/ 2π f C
= 1/ 2π * f Hz * 10.8μF
= _____ Ω
Irms = 120 V / XC Ω
= ____
c ) Maximum rms current Irms = Vrms / XC
XC = 1/ 2π f C
= 1/ 2π * f Hz * 22.0μF
= ___ Ω
Irms = 120 V / XC Ω
 
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What value frequency did you calculate? What did they provide as the correct answer?

Why do you divide by Xc to get the current?
 
scottdave said:
What value frequency did you calculate? What did they provide as the correct answer?

Why do you divide by Xc to get the current?
Note that Post #1 is dated 1 April 2010!
 
Steve4Physics said:
Note that Post #1 is dated 1 April 2010!
Ha! :woot: These Unanswered Questions just show up... and I'm so into trying to help - I forget to look at the date.
 
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