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

Answer: (C)

$R = 15 \Omega, L = 3.5 H , C = 30 \mu F$

Answer 2

For better tuning quality factor should be high
$Q = \frac{1}{R} \sqrt{\frac{L}{C}}$
for $Q_{max}$, R should be least
$\therefore$ Best answer is
$R = 15 \; \Omega, L = 3.5 H, C = 30 \mu F$