📊 PYQ Analysis

10 Years

Last 10 years of CBSE, NEET, JEE Main, and JEE Advanced — topic-wise weightage, recurring patterns, and difficulty distribution. This is your cheat sheet for what actually gets asked.

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Strategy Tip — How to Use PYQ Data

Don't just read PYQs. Analyze the pattern. If Doppler Effect appears in JEE Main 8 out of 10 years, it's not optional. If organ pipe harmonics dominate NEET, those 5 formula variations are must-know. Focus energy where frequency × marks = maximum ROI.

CBSE Boards — Topic Weightage (Last 10 Years)

📊 Topic-wise Frequency

Speed of Sound (Newton/Laplace)

90%

Resonance Tube Experiment

85%

Organ Pipes (harmonics)

80%

Doppler Effect (numericals)

75%

Beat Frequency

70%

Standing Waves in Strings

65%

✅ Guaranteed Questions

Newton's/Laplace's correction derivation — 3-mark question. Appears 9/10 years.

Resonance tube numerical — 2 resonance lengths given, find v. Appears 8/10 years.

Doppler numerical — Train with whistle. Appears 7/10 years.

📝 Question Types

1-mark: Define beat frequency, state Laplace correction, write wave equation.

2-mark: Resonance tube calculation, beat problem with wax.

3-mark: Derivation of v in gases. Comparison of Newton vs Laplace.

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CBSE Trap Question (2022)

"Why does the speed of sound in air increase with humidity?" Most students say "water is denser" — WRONG. Answer: Water vapour (M=18) has lower molar mass than dry air average (~29), so v = √(γRT/M) increases. Density argument alone is incomplete and gets zero marks.

NEET — Topic Weightage (Last 10 Years)

📊 Topic-wise Frequency

Beats & Tuning Forks

95%

Organ Pipe Harmonics/Overtones

90%

Doppler Effect

80%

Speed of Sound in Gas

75%

Resonance Tube

70%

3–4

Questions per year

12–16

Marks from Waves

~90%

Single-concept MCQs

🔥 Recurring NEET Question Patterns

Beats with wax: Fork A gives n beats with 512 Hz. After loading with wax, beats become n±2. Find original frequency. — Appears ~8/10 years.

Closed pipe harmonics: "Which harmonics are absent in a closed pipe?" or "Find the 3rd overtone frequency of a closed pipe of length 0.5m." — Appears 7/10 years.

Doppler sign convention: Observer moving toward stationary source — find apparent frequency. Simple number substitution. Appears 6/10 years.

Sound speed temperature change: Speed at T₁ = 300 m/s. Find speed at 4T₁ (Kelvin). v ∝ √T → answer = 600 m/s. Appears 5/10 years.

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NEET 2023 — Actual Question Pattern

A string of length L is fixed at both ends. If the speed of waves in the string is v, the frequencies of standing waves are: (A) nv/L (B) nv/2L (C) 2nv/L (D) (2n-1)v/4L. Answer: (B). This type appears every year — identify pipe/string type, apply correct formula.

JEE Main — Topic Weightage (Last 10 Years)

📊 Topic-wise Frequency

Doppler Effect

90%

Wave Equation Analysis

80%

Standing Waves / Resonance

75%

Superposition / Intensity

70%

Beats

65%

Sound Intensity / dB

55%

📅 Year-wise Topics (Recent)

2024

2023

2022

2021

2020

2019

2018

2017

Click a year to see topics tested.

⚡ Integer-Type Patterns (JEE Main)

Beat frequency: Two pipes of given lengths. Find number of beats. Integer answer = |f₁−f₂|.

Intensity ratio: Two waves with amplitude ratio 1:3. I_max/I_min = (3+1)²/(3-1)² = 4.

Harmonic identification: Standing wave with x nodes. Which harmonic? Answer = nodes−1.

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JEE Main 2022 Trap

Question: "A source of frequency f₀ moves away from a stationary observer at speed v_s. The observer starts moving toward the source at speed v_o. Both simultaneously. Find apparent frequency." Answer requires BOTH observer numerator AND source denominator terms. Most students apply only one.

JEE Advanced — Depth Analysis

💀 Question Types (Advanced)

Paragraph-based: 3 sub-questions from same setup. Common setup: two speakers, changing phase, asking for interference pattern changes.

Multi-correct MCQ: Which of the following are true about a standing wave? Requires knowing 4–5 properties simultaneously.

Numerical answer: Usually coupling Doppler + relative kinematics or string tension + thermal expansion of metal.

📚 Key JEE Advanced Papers Decoded

2015

Interference of two sound sources. Variation of intensity with position of observer. Required understanding of path difference geometry.

2018

Resonant cavity with two closed ends — identified as acoustic resonance problem combining Thermodynamics (γ value matters).

2021

Doppler with relativistic hint. Source moving at high fraction of v_sound — standard formula gives wrong limit, needed correction at v_s → v.

2023

Phase shift on reflection from rigid boundary (π shift). Used to determine condition for resonance in a tube with one rigid + one open end.

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JEE Advanced Pattern — What They Keep Testing

1. Phase shift at boundaries (π at rigid, 0 at free)
2. Doppler with acceleration (instantaneous f calculation)
3. Multi-source interference with non-standard geometry
4. Resonance with end correction and temperature correction
These 4 themes repeat every 2–3 years. Master these and you've mastered JEE Advanced Waves.

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