NEET-XII-Physics
39: Alternating Current
- #2The reactance of a circuit is zero. It is possible that the circuit contains
(a) an inductor and a capacitor
(b) an inductor but no capacitor
(c) a capacitor but no inductor
(d) neither an inductor nor a capacitordigAnsr: a,d,b,cAns : (a) an inductor and a capacitor
(d) neither an inductor nor a capacitor
(a) The reactance of a circuit containing a capacitor and an inductor is given by,
`` X={X}_{L}-{X}_{C}=\omega L-\frac{1}{\omega C}``
`` ``
If `` \omega L=\frac{1}{\omega C}``, X = 0. So, the circuit contains an inductor and a capacitor.
(b) For a circuit without a capacitor, reactance is given by,
`` {X}^{\text{'}}={X}_{L}=\omega L``, which cannot be zero for an AC source.
(c) Similarly, for a circuit without an inductor, reactance is given by,
`` {X}^{\text{'}\text{'}}={X}_{C}=\frac{1}{\omega C}``, which also cannot be zero.
(d) For a circuit without any capacitor and inductor, reactance, X' = 0 ( L = C = 0)
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