To an ac power supply of 220 V at 50 Hz, a resistor of 20Ω , a capacitor of reactance 25Ω and an inductor of reactance 45Ω are connected in series. The corresponding current in the circuit and the phase angle between the current and the voltage is, respectively-

Physics · Alternating Current

NEET (UG) 2025 — Question 15

To an ac power supply of 220 V at 50 Hz, a resistor of $20\Omega$ , a capacitor of reactance $25\Omega$ and an inductor of reactance $45\Omega$ are connected in series. The corresponding current in the circuit and the phase angle between the current and the voltage is, respectively-

Option A:
7.8 A and $30^{\circ}$
Option B:
7.8 A and $45^{\circ}$
Correct
Option C:
15.6 A and $30^\circ$
Option D:
15.6 A and $45^\circ$

Answer: B

Step-by-step solution

$\mathrm{X}_{\mathrm{C}}=25 \Omega$

$X_{L}=45 \Omega$

$Z=\sqrt{R^{2}+\left(X_{L}-X_{C}\right)^{2}}$

$Z=\sqrt{20^{2}+(45-25)^{2}}$ $Z=20 \sqrt{2}$

$I_{\mathrm{rms}}=\frac{V_{\mathrm{rms}}}{Z}=\frac{220}{20 \sqrt{2}}=\frac{11}{\sqrt{2}}=7.8 \mathrm{~A}$

$\tan \phi=\frac{X_{L}-X_{C}}{R}=\frac{45-25}{20}=\frac{20}{20}=1$

$\phi=45^{\circ}$

Answer key and solution verified before publishing.

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Exam: NEET (UG) 2025
Paper: 2025 paper
Subject: Physics
Chapter: Alternating Current
Topic: Series LCR Circuit and Power Factor