Q134 / 150 · MHT CET 2024 (11 May Shift 1) · Physics

With gradual increase in frequency of an a.c. supply, the impedance of an LCR series circuit

  • A
    increases.
  • B
    decreases.
  • C
    remains constant
  • Correct answer
    D
    first decreases, becomes minimum and then increases.

Solution

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

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

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