GROL Electrical Principles and Units 4

Question 1

What is the resonant frequency of a circuit with L = 100 μH and C = 100 pF?

Accepted Answer

1.59 MHz

Answer

f = 1/(2π√(LC)) = 1/(2π√(10⁻¹⁴)) ≈ 1.59 MHz.

Question 2

At resonance in a series RLC circuit, the total impedance equals:

Accepted Answer

The resistance R alone

Answer

At resonance XL = XC, they cancel, and impedance reduces to R alone.

Question 3

How is the Q factor of a series resonant circuit defined?

Accepted Answer

Q = XL/R

Answer

Q = XL/R, representing the ratio of reactance to resistance at resonance.

Question 4

A resonant circuit has a center frequency of 1 MHz and a 3-dB bandwidth of 10 kHz. What is its Q factor?

Accepted Answer

100

Answer

Q = f₀/BW = 1,000,000/10,000 = 100.

Question 5

What is the RMS value of a sine wave with a peak voltage of 170 V?

Accepted Answer

120 V

Answer

Vrms = Vpeak/√2 = 170/1.414 ≈ 120 V, which is standard US household voltage.

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