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MHT CET · Physics · Alternating Current

With increase in frequency of a.c. supply, the impedance of an \(\mathrm{L}-\mathrm{C}\)-R series circuit

  1. A remains constant.
  2. B increases.
  3. C decreases.
  4. D decreases at first, becomes minimum and then increases.
Verified Solution

Answer & Solution

Correct Answer

(D) decreases at first, becomes minimum and then increases.

Step-by-step Solution

Detailed explanation

We know
\(\mathrm{X}_{\mathrm{L}}=\mathrm{L} \omega\) and \(\mathrm{X}_{\mathrm{C}}=\frac{1}{\mathrm{C} \omega}\)
\(\Rightarrow\) When the frequency increases, \(X_{\mathrm{L}}^{\prime}\) increases and \(X_c\) decreases.
\(\therefore \quad\) The impédance of an LCR series circuit decreases at first, becomes minimum and then increases.