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🌊 WAVES (Mechanical Waves)

Objective Questions – Page 8 (Very Tough)

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Q71️⃣ (Wave + Particle Motion)

In a progressive wave travelling in +x direction, particles of the medium:

• A) Move in +x direction continuously
• B) Move in −x direction continuously
• C) Oscillate about mean position
• D) Remain stationary

Answer: C

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Q72️⃣ (Numerical – Phase Difference)

Phase difference between two points separated by λ/6 is:

• A) π/6
• B) π/3
• C) 2π/3
• D) π

Answer: B

Logic: Δφ = 2πx/λ = 2π(1/6) = π/3

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Q73️⃣ (Standing Wave – Nodes)

Distance between two consecutive nodes in a standing wave is:

• A) λ
• B) λ/2
• C) λ/4
• D) 2λ

Answer: C

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Q74️⃣ (Speed of Sound – Concept)

Speed of sound in air depends on:

• A) Pressure only
• B) Density only
• C) Temperature only
• D) Temperature and humidity

Answer: D

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Q75️⃣ (Doppler Effect – Numerical)

A source emitting 500 Hz sound approaches a stationary observer with speed v/5 (v = speed of sound). Observed frequency is approximately:

• A) 556 Hz
• B) 625 Hz
• C) 500 Hz
• D) 450 Hz

Answer: A

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Q76️⃣ (Beats – Logic)

Maximum beats are heard when:

• A) Frequencies are equal
• B) Frequency difference is maximum
• C) Amplitudes are equal
• D) Frequencies differ slightly

Answer: D

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Q77️⃣ (Organ Pipe – Closed)

Which harmonics are present in a closed organ pipe?

• A) All harmonics
• B) Only even harmonics
• C) Only odd harmonics
• D) No harmonics

Answer: C

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Q78️⃣ (Wave Equation – Trap)

For y = A sin(ωt + kx), the wave travels:

• A) Along +x
• B) Along −x
• C) Perpendicular to x
• D) Stationary

Answer: B

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Q79️⃣ (Sound Intensity)

If amplitude of sound wave doubles, intensity becomes:

• A) Double
• B) Half
• C) Four times
• D) Eight times

Answer: C

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Q80️⃣ (Conceptual – Tough)

Which of the following does NOT change on reflection of a wave?

• A) Speed
• B) Frequency
• C) Direction
• D) Phase

Answer: B

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✅ Objective Page 8 Completed
Level: ⭐⭐⭐⭐⭐ (JEE Advanced)

👉 Type Objective Page 9 to continue