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

Options

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`

Explanation

To determine the best combination for better tuning of an LCR circuit used for communication, we need to focus on the quality factor (Q) of the circuit. The quality factor is a measure of the sharpness of the resonance peak of the circuit, and a higher Q indicates better tuning and selectivity.

### Step-by-Step Solution:

1. **Understand the Quality Factor (Q)**:
The quality factor (Q) of an LCR circuit is defined as:
\[ Q = \frac{1}{R} \sqrt{\frac{L}{C}} \]
where:
- \( R \) = resistance in ohms (Ω)
- \( L \) = inductance in henries (H)
- \( C \) = capacitance in farads (F)

2. **Identify the Conditions for High Q**:
For the quality factor \( Q \) to be high:
- The resistance \( R \) should be low.
- The inductance \( L \) should be high.
- The capacitance \( C \) should also be considered, but primarily we focus on minimizing \( R \) and maximizing \( L \).

3. **Evaluate Given Options**:
Assume we have four options with different values of \( R \), \( L \), and \( C \). We need to select the combination that has the lowest resistance \( R \) and the highest inductance \( L \).

4. **Select the Best Combination**:
- Compare the resistance values: Choose the option with the lowest \( R \).
- Compare the inductance values: Choose the option with the highest \( L \).
- The combination that meets these criteria will yield the highest quality factor \( Q \).

5. **Conclusion**:
After analyzing the options, if we find that one option has \( R = 15 \, \Omega \) (the lowest) and \( L = 3.5 \, H \) (the highest), then this option will provide the best tuning for the LCR circuit used in communication.

### Final Answer:
The best combination for better tuning of an LCR circuit used for communication is option 3, which has a resistance of 15 ohms and an inductance of 3.5 henries.

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