Question

Which of the following combinations should be selected for better tuning of an LCR circuit used for communication?

• A. \( R = 20 \, \Omega, L = 1.5 \, \text{H}, C = 35 \, \mu\text{F} \)
• B. \( R = 25 \, \Omega, L = 2.5 \, \text{H}, C = 45 \, \mu\text{F} \)
• C. \( R = 25 \, \Omega, L = 1.5 \, \text{H}, C = 45 \, \mu\text{F} \)
• D. \( R = 15 \, \Omega, L = 3.5 \, \text{H}, C = 30 \, \mu\text{F} \)

Answer 1

The Correct Option is D

The \( Q \)-factor of an LCR circuit is an important parameter for communication systems as it determines the sharpness of resonance. The quality factor is given by the formula:
\( Q = \frac{1}{R} \sqrt{\frac{L}{C}} \).

For higher \( Q \)-factors (which are desirable for better tuning), we require a lower resistance and larger inductance and capacitance values. 
After calculating the \( Q \)-factor for each combination, the combination in option (D) yields the highest \( Q \)-factor, which is ideal for tuning in communication circuits.