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A 13.6- resistor, an 11.9-μF capacitor, and a 19.1-mH inductor are connected in series with a 117-V generator. (a) At what frequency
Question
A 13.6- resistor, an 11.9-μF capacitor, and a 19.1-mH inductor are connected in series with a 117-V generator.
(a) At what frequency is the current a maximum?
(b) What is the maximum value of the RMS current?
Note: The ac current and voltage are RMS values and power is an average value unless indicated otherwise.
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Physics
4 years
2021-07-31T06:15:57+00:00
2021-07-31T06:15:57+00:00 2 Answers
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Answers ( )
Answer:
a) Current is maximum at frequency, f₀ = 333.83 Hz
b) Maximum current = 12.17 A
Explanation:
Inductance, L = 19.1 mH = 19.1 * 10⁻³ H
Capacitance, C = 11.9 μF =11.9 * 10⁻⁶ F
a) Current is maximum at resonant frequency, f₀
b) Maximum value of the RMS current
Answer:
Explanation:
Given the following information,
Resistor of resistance R = 13.6Ω
Capacitor of capacitance C = 11.9-μF
C = 11.9 × 10^ -6 F
Inductor of inductance L = 19.1-mH
L = 19.1 ×10^-3 H
All this connected in series to a generator that generates Vrms= 117V
Vo = Vrms√2 = 117√2
Vo = 165.463V
a. Frequency for maximum current?
Maximum current occurs at resonance
I.e Xc = XL
At maximum current, the frequency is given as
f = 1/(2π√LC)
Then,
f = 1/(2π√(19.1×10^-3 × 11.9×10^-6)
f = 1/(2π√(2.2729×10^-7))
f = 1/(2π × 4.77 ×10^-4)
f = 333.83Hz
Then, the frequency is 333.83Hz.
b. Since we know the frequency,
Then, we need to find the capacitive and inductive reactance
Capacitive reactance
Xc = 1/2πfC
Xc = 1/(2π × 338.83 × 11.9×10^-6)
Xc = 1/ 0.024961
Xc = 40.1Ω
Also, Inductive reactance
XL = 2πfL
XL = 2π × 333.83 × 19.1×10^-3
XL = 40.1Ω
As expected, Xc=XL, resonance
Then, the impedance in AC circuit is given as
Z = √ (R² + (Xc—XL)²)
Z = √ 13.6² + (40.1-40.1)²)
Z = √13.6²
Z = 13.6 ohms
Then, using ohms las
V = IZ
Then, I = Vo/Z
Io = 165.46/13.6
Io = 12.17Amps
The current is 12.17 A