Q147 / 180 · KCET 2024 · Physics

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

  • A
    $R=20 \Omega L=1.5 \mathrm{H}, C=35 \mu \mathrm{~F}$
  • B
    $R=25 \Omega L=2.5 \mathrm{H}, C=45 \mu \mathrm{~F}$
  • C
    $R=25 \Omega, L=1.5 \mathrm{H}, C=45 \mu \mathrm{~F}$
  • Correct answer
    D
    $R=15 \Omega L=3.5 \mathrm{H}, C=30 \mu \mathrm{~F}$

Solution

For better tunning of an $L-C-R$ circuit used in for communication, quality factor $Q$ must be high. $\therefore \quad Q=\frac{1}{R} \sqrt{\frac{L}{C}}$ In option (4), $R$ and $C$ is minimum and $L$ is maximum. Thus, the value of $R, L$ and $C$ given in option (4) suitable for better communication.

Hence, the correct answer is option: 'D'.

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