Question

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

• A. $R=25\Omega ,L=1\cdot 5H,C=45\mu F$
• B. $R=25\Omega ,L=1.5H,C=35\mu F$
• C. $R=25\Omega ,L=2.5H,C=45\mu F$
• D. $R=15\Omega ,L=3.5H,C=30\mu F$

Answer 1

The correct option is D $R=15\Omega ,L=3.5H,C=30\mu F$

For tuning a LCR circuit, its selectivity should be high. High selectivity is observed in circuits with high quality factor.
$Q=\frac{\sqrt{L}}{R\sqrt{C}}$
For option (a), $Q=7.3$
For option (b), $Q=8.28$
For option (c), $Q=9.43$
For option (d), $Q=22.77$

Hence, option (d) gives the best combination.