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Zorluk: OrtaAlternating Current (AC) Circuits

A series alternating current (AC) circuit contains an inductor of inductance L=1π2 HL = \frac{1}{\pi^2}\ \text{H}, a capacitor of capacitance C=25 μFC = 25\ \mu\text{F}, and a resistor of resistance R=50 ΩR = 50\ \Omega. What is the resonant frequency of the circuit in hertz (Hz\text{Hz})?

Cevap: 100 Hz

Cevap

The resonant frequency of the circuit is 100 Hz100\ \text{Hz}.
At resonance, the inductive reactance XL=2πfLX_L = 2\pi f L equals the capacitive reactance XC=12πfCX_C = \frac{1}{2\pi f C}. Equating both yields f0=12πLCf_0 = \frac{1}{2\pi\sqrt{LC}}. Substituting L=1π2 HL = \frac{1}{\pi^2}\ \text{H} and C=25×106 FC = 25 \times 10^{-6}\ \text{F} gives LC=5×103π s\sqrt{LC} = \frac{5 \times 10^{-3}}{\pi}\ \text{s}, leading to f0=12π(5×103π)=100 Hzf_0 = \frac{1}{2\pi \left(\frac{5 \times 10^{-3}}{\pi}\right)} = 100\ \text{Hz}.

Adım Adım Çözüm

1
Write down the formula for the resonant frequency of a series RLC circuit.
f0=12πLCf_0 = \frac{1}{2\pi\sqrt{LC}}
Resonance occurs when the inductive reactance equals the capacitive reactance (XL=XCX_L = X_C).
2
Substitute the values of inductance L=1π2 HL = \frac{1}{\pi^2}\ \text{H} and capacitance C=25×106 FC = 25 \times 10^{-6}\ \text{F} into LC\sqrt{LC}.
LC=1π2×25×106=5×103π s\sqrt{LC} = \sqrt{\frac{1}{\pi^2} \times 25 \times 10^{-6}} = \frac{5 \times 10^{-3}}{\pi}\ \text{s}
Simplifying the square root removes the fraction containing π\pi.
3
Calculate the resonant frequency f0f_0.
f0=12π×5×103π=1102=100 Hzf_0 = \frac{1}{2\pi \times \frac{5 \times 10^{-3}}{\pi}} = \frac{1}{10^{-2}} = 100\ \text{Hz}
The factor of π\pi cancels out in the denominator, resulting in a whole number value.

Anahtar Kavram

Resonant Frequency in AC Series Circuits
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