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Physics

Alternating Current

AC circuits with resistors, inductors, and capacitors build up to the series LCR circuit, resonance, power factor, and the transformer. NEET numericals target impedance, resonant frequency, and average power, with occasional recall on transformer ratios.

Exam rules change between cycles. Confirm dates, syllabus and pattern against NTA's official site. We are not NTA.

Weightage: what the paper actually did

Alternating Current carried 2 questions in the NEET 2026 paper. One paper is a data point, not a destiny: NTA moves weight between chapters every cycle, which is why the weightage tables deserve care. The stable facts are the paper's shape: 180 questions, 720 marks, +4 right, −1 wrong.

Sample PYQs from this chapter

Real questions NTA asked from Alternating Current, with the answer and the working. Try before you peek.

Question 1 · NEET 2026

An ac circuit contains a resistance of 1 kΩ\Omega, a capacitor of 0.1 μ\muF and an inductor of 1 mH connected in series. The resonance frequency of the circuit is approximately:
  1. A.13.5 kHz
  2. B.10.1 kHz
  3. C.20.7 kHz
  4. D.15.9 kHz
Answer and explanation

Answer: D

Series resonance occurs at f0=12πLCf_0 = \dfrac{1}{2\pi\sqrt{LC}}, which is independent of the resistance. With L=1 mH=10−3 HL = 1\ \text{mH} = 10^{-3}\ \text{H} and C=0.1 μF=10−7 FC = 0.1\ \mu\text{F} = 10^{-7}\ \text{F}, f0=12π10−10=12π×10−5≈15.9 kHzf_0 = \dfrac{1}{2\pi\sqrt{10^{-10}}} = \dfrac{1}{2\pi \times 10^{-5}} \approx 15.9\ \text{kHz} (option D). The resistance value is a distractor since it does not enter the resonance formula.

Question 2 · NEET 2026

The peak value of an alternating current is 5 A5\ \text{A} and frequency is 60 Hz60\ \text{Hz}. How long will the current, starting from zero, take to reach the peak value?
  1. A.1120 s\dfrac{1}{120}\ \text{s}
  2. B.160 s\dfrac{1}{60}\ \text{s}
  3. C.130 s\dfrac{1}{30}\ \text{s}
  4. D.1240 s\dfrac{1}{240}\ \text{s}
Answer and explanation

Answer: D

With i=ipeaksin⁡(ωt)i = i_{peak}\sin(\omega t) and ω=2πf=120π rad/s\omega = 2\pi f = 120\pi\ \text{rad/s}, the current first equals its peak when sin⁡(ωt)=1\sin(\omega t) = 1, i.e. ωt=π/2\omega t = \pi/2. This gives t=14f=14×60=1240 st = \dfrac{1}{4f} = \dfrac{1}{4 \times 60} = \dfrac{1}{240}\ \text{s} (a quarter of the period). Why the other options are wrong: - (A) Half-period 1/2f1/2f; that is the time to return to zero, not to reach the peak. - (B) Full period 1/f1/f. - (C) Twice the period; dimensionally the wrong fraction.

How to practise Alternating Current

Chapter by chapter, against real past-paper questions, on a screen: NEET is computer based from 2027. Read the chapter once, then attempt its PYQs until your accuracy stops climbing, and let the wrong answers tell you which lines to reread. If the chapter keeps refusing to stick, that has its own guide. There is also a free 12-question mock on the exam screen.

Nearby Physics chapters

Questions

How many questions did Alternating Current have in NEET 2026?

Alternating Current carried 2 questions in the NEET 2026 paper. Weightage shifts between cycles, so treat it as a probability, not a promise.

Where can I practise Alternating Current PYQs for NEET?

In the BrainIt app, free until the 2027 exam: its bank holds 50,000 past NTA questions tagged to all 83 chapters, including this one, with accuracy tracked per chapter. Sample questions from this chapter are on this page.

Is Alternating Current important for NEET 2027?

It is part of the Physics syllabus the paper draws from, and NEET 2027 is computer based, so practise it on a screen. Your own accuracy in the chapter matters more than any weightage table: a heavy chapter you already score well on needs less time than a light one you keep missing.

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