Q122 / 160 · JIPMER 2010 · Physics
The impedance of a circuit, when a resistance $R$ and an inductor of inductance $L$ are connected in series in an AC circuit of frequency $f$, is
- A$\sqrt{R+2 \pi^2 f^2 L^2}$
- B$\sqrt{R+4 \pi^2 f^2 L^2}$
- Correct answerC$\sqrt{R^2+4 \pi^2 f^2 L^2}$
- D$\sqrt{R^2+2 \pi^2 f^2 L^2}$
Solution
In $L-R$ circuit,
Impedance $Z=\sqrt{R^2+X_L^2}$
Here, $\quad X_L=\omega L=2 \pi f L$
$\therefore \quad Z=\sqrt{R^2+4 \pi^2 f^2 L^2}$
Hence, the correct answer is option: 'C'.