Question

Which of the following combinations should be selected for better tuning of an $L-C-R$ circuit used for communication ?

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

Answer 1

The Correct Option is C

Quality Factor and Tuning 

For better tuning of an electrical circuit, the quality factor (Q) should be high. The quality factor is a measure of the resonance sharpness of a circuit, and it depends on the resistance \( R \), inductance \( L \), and capacitance \( C \). The formula for the quality factor \( Q \) is given by:

\(Q = \frac{1}{R} \sqrt{\frac{L}{C}}\)

For Maximum Quality Factor:

• For \( Q \) to be maximum, the value of \( R \) should be minimized.
• A lower resistance leads to a higher quality factor and better tuning quality in the circuit.

Given Values:

The given values for the components are:

• \(R = 15 \; \Omega\)
• \(L = 3.5 \; \text{H}\)
• \(C = 30 \; \mu \text{F}\)

Conclusion:

To achieve the best tuning, the resistance \( R \) should be as low as possible, and with the given values of \( R \), \( L \), and \( C \), the quality factor \( Q \) will be optimized for the best tuning.