Chapter 11: Sound Application Questions | science Class 9 CBSE

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Chapter 11: Sound Application Questions | science Class 9 CBSE | ByteNotes.in

Application Question

Concept in a practical situation

Application

Question 1

Applied Concept

Q1. Define sound and state its nature of wave.

Sound is a form of energy that produces a sensation of hearing.
It is a mechanical wave: needs medium to travel.
It is longitudinal: particles vibrate parallel to direction of wave.
Created by vibrating objects.
Cannot travel through vacuum.

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Application Question

Concept in a practical situation

Application

Question 2

Applied Concept

Q2. State conditions necessary for echo formation.

Time gap must be ≥ 0.1 sec for echo to be heard.
Speed of sound in air ≈ 343 m/s.
Minimum distance = 17.2 m (343 × 0.1 / 2).
Hard reflecting surface required.
Original and reflected sounds must not overlap.

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Application Question

Concept in a practical situation

Application

Question 3

Applied Concept

Q3. Write differences between longitudinal and transverse waves.

Longitudinal: vibrations parallel to wave motion.
Transverse: vibrations perpendicular to motion.
Sound is longitudinal; light is transverse.
Longitudinal can travel in solids, liquids, gases.
Transverse mostly in solids and vacuum (e.g., EM waves).

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Application Question

Concept in a practical situation

Application

Question 4

Applied Concept

Q4. Derive relationship between speed, frequency, and wavelength.

Let v = speed, f = frequency, λ = wavelength.
Wave travels one wavelength in one time period.
v = f × λ.
As frequency or wavelength increases, speed increases.
Used for all wave types (sound, light, etc.).

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Application Question

Concept in a practical situation

Application

Question 5

Applied Concept

Q5. How does sound travel through solids, liquids, and gases?

Solids: fastest due to tightly packed particles.
Liquids: slower than solids.
Gases: slowest due to sparse particles.
Speed order: solids > liquids > gases.
Medium’s elasticity and density affect speed.

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Application Question

Concept in a practical situation

Application

Question 6

Applied Concept

Q6. Define amplitude, frequency, and wavelength.

Amplitude: max displacement of particles from rest.
Frequency: number of vibrations per second (Hz).
Wavelength: distance between two consecutive compressions/rarefactions.
Amplitude → loudness; frequency → pitch.
These determine characteristics of sound.

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Chapter sections

Chapter 11: Sound | Application Questions

Q1. Define sound and state its nature of wave.

Q2. State conditions necessary for echo formation.

Q3. Write differences between longitudinal and transverse waves.

Q4. Derive relationship between speed, frequency, and wavelength.

Q5. How does sound travel through solids, liquids, and gases?

Q6. Define amplitude, frequency, and wavelength.

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