Alternating Current Ques 24

24. A capacitor has capacity $C$ and reactance $X$. If capacitance and frequency become double, then reactance will be

[2001]

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Answer:

Correct Answer: 24.(c)

Solution:

  1. (c) Capacitive reactance, $X=\frac{1}{\omega C}=\frac{1}{2 \pi f C}$

$\Rightarrow X \propto \frac{1}{f C}$

$\therefore \frac{X^{\prime}}{X}=\frac{f}{f^{\prime}} \times \frac{C}{C^{\prime}}=\frac{f}{2 f} \times \frac{C}{2 C}=\frac{1}{4}$

$\Rightarrow X^{\prime}=\frac{X}{4}$