Quantrex Quantrex AcademyJEE · NEET · NDA PYQs with solutions Open app
NEET 2026
Exam
NEET
Year
2026
Subject
Physics
Chapter
Chapter

NEET 2026 · Physics · Chapter

An alternating voltage given by V = 120 (2000t) is applied across a...

An alternating voltage given by V=120sin⁡(2000t)V = 120 \sin(2000t) is applied across a series LCR circuit containing an inductor of 0.1 H0.1\text{ H}, a capacitor of 10 μF10\ \mu\text{F}, and a resistor of 40 Ω40\ \Omega. Let ν0\nu_0 be the resonant frequency of this circuit. Which of the following options correctly gives the value of ν0\nu_0 and describes the phase of the current relative to the applied voltage at the given source frequency?

Options

  1. Aν0=1000π Hz\nu_0 = \dfrac{1000}{\pi}\text{ Hz}; current leads the voltage
  2. Bν0=500π Hz\nu_0 = \dfrac{500}{\pi}\text{ Hz}; current leads the voltage
  3. Cν0=500π Hz\nu_0 = \dfrac{500}{\pi}\text{ Hz}; current lags the voltage
  4. Dν0=1000 Hz\nu_0 = 1000\text{ Hz}; current lags the voltage

Correct answer

C. ν0=500π Hz\nu_0 = \dfrac{500}{\pi}\text{ Hz}; current lags the voltage

Step-by-step solution

Given V=120sin⁡(2000t)V = 120 \sin(2000t), the angular frequency of the source is ω=2000 rad/s\omega = 2000\text{ rad/s}.

The resonant angular frequency is given by ω0=1LC\omega_0 = \dfrac{1}{\sqrt{LC}}.

Substituting the given values L=0.1 HL = 0.1\text{ H} and C=10 μF=10−5 FC = 10\ \mu\text{F} = 10^{-5}\text{ F}:

ω0=10.1×10−5=110−6=1000 rad/s\omega_0 = \dfrac{1}{\sqrt{0.1 \times 10^{-5}}} = \dfrac{1}{\sqrt{10^{-6}}} = 1000\text{ rad/s}

The resonant frequency ν0\nu_0 is:

ν0=ω02π=10002π=500π Hz\nu_0 = \dfrac{\omega_0}{2\pi} = \dfrac{1000}{2\pi} = \dfrac{500}{\pi}\text{ Hz}

To find the phase relationship at the source frequency ω=2000 rad/s\omega = 2000\text{ rad/s}, we calculate the inductive and capacitive reactances:

XL=ωL=2000×0.1=200 ΩX_L = \omega L = 2000 \times 0.1 = 200\ \Omega

XC=1ωC=12000×10−5=50 ΩX_C = \dfrac{1}{\omega C} = \dfrac{1}{2000 \times 10^{-5}} = 50\ \Omega

Since XL>XCX_L > X_C, the circuit is predominantly inductive at this frequency.

In an inductive circuit, the current lags the applied voltage.

Answer: ν0=500π Hz\nu_0 = \dfrac{500}{\pi}\text{ Hz}; current lags the voltage
Practice Chapter on Quantrex Academy →

More from Chapter

A solid spherical body of radius R , density ρ , and specific heat capacity s is… NEET 2026A straight canal has motorboats departing from two terminals at opposite ends. The… NEET 2026A wooden crate is released from rest at the top of a ramp inclined at 37^ ∘ to the… NEET 2026A uniform horizontal beam of mass 6 kg and length L is hinged to a vertical wall at one… NEET 2026A bullet P of mass 30 g moving with a speed of 200 m/s penetrates a target and comes to… NEET 2026A small block of mass m is placed at the highest point of a smooth fixed sphere of radius… NEET 2026A block of mass 2 kg is projected with an initial speed of 14 m/s on a rough horizontal… NEET 2026A uniform horizontal circular disc of mass M and radius R is rotating freely about a… NEET 2026 Full Chapter list All NEET PYQs