AdvancedA-001-005-003
What is the Q of a parallel RLC circuit, if it is resonant at 4.468 MHz, L is 47 microhenrys and R is 180 ohms?
C
Answer
Advanced theory and components
Type
A
7.35
B
0.00735
C
0.136
D
13.3
Answer Notes
The Quality factor (Q) for a parallel RLC circuit is determined by the ratio of its parallel resistance to its reactance: Q = R / X_L.
First, compute the inductive reactance using X_L = 2 π f L. Substituting the given values gives 2 × π × 4.468 × 10⁶ Hz × 47 × 10⁻⁶ H. As the micro and mega prefixes cancel, this becomes 2 × π × 4.468 × 47, which equals approximately 1319.4 ohms.
Next, apply the parallel Q formula. Divide the given resistance of 180 ohms by the calculated reactance of 1319.4 ohms. This results in 180 / 1319.4 ≈ 0.136. Because the parallel resistance is lower than the reactance, the circuit is heavily damped and has a Q of less than 1.
Previous · A-001-005-002
What is the Q of a parallel RLC circuit, if it is resonant at 14.128 MHz, L is 4.7 microhenrys and R is 18 kilohms?
Next · A-001-005-004
What is the Q of a parallel RLC circuit, if it is resonant at 14.225 MHz, L is 3.5 microhenrys and R is 10 kilohms?