Target Exam

CUET

Subject

Physics

Chapter

Alternating Current

Question:

Which combination is to be selected for better tuning of an LCR series circuit used for communication?

Options:

$R=20Ω, L=1.5 H, C=35 μF$

$R=25Ω, L=2.5 H, C=45 μF$

$R=15Ω, L=3.5 H, C=30 μF$

$R=15Ω, L=1.5 H, C=45 μF$

Correct Answer:

$R=15Ω, L=3.5 H, C=30 μF$

Explanation:

The correct answer is Option (3) → $R=15Ω, L=3.5 H, C=30 μF$

for resistance in an LCR series circuit,

$f_0=\frac{1}{2\pi\sqrt{LC}}$

$f_0$ = Resonant frequency

L = Inductance

C = Capacitance

for, $L=3.5 H$ and $C=30μF$

$f_0=\frac{1}{2\pi\sqrt{3.5×30×10^{-6}}}≃859.9Hz$

and, the resonant frequency ($f_0$) is greater than compare to others when,

$R=15Ω, L=3.5 H, C=30 μF$