CBSE-XI-Physics
39: Alternating Current
- #12Can you have an AC series circuit in which there is a phase difference of (a) 180° (b) 120° between the emf and the current?Ans : Let us consider an AC series LCR circuit of angular frequency ω. The impedance of the circuit is given by,
`` Z=\sqrt{{R}^{2}+{\left(\omega L-\frac{1}{\omega C}\right)}^{2}}``
The phase difference between V and I is given by,
`` \,\mathrm{\,tan\,}\varphi =\left(\frac{\omega L-{\displaystyle \frac{1}{\omega C}}}{Z}\right)``
From the above formula, we can clearly see that
`` \varphi \in \left(-\frac{\,\mathrm{\,\pi \,}}{2},\frac{\,\mathrm{\,\pi \,}}{2}\right)``
So, we cannot have a phase difference of 180° or 120°.
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