Introduction
Sound is an important chapter of Class 10 Physics that explains how sound waves are produced, transmitted, and detected. Sound is a mechanical wave created by vibrating objects and requires a medium such as air, water, or solids for propagation. This chapter helps students understand the properties of sound waves and their applications in daily life.
Students learn about important concepts such as frequency, wavelength, amplitude, pitch, loudness, quality of sound, echo, reverberation, and ultrasound. The chapter also explains how the speed of sound changes in different media and how sound waves are used in technologies such as sonar, medical imaging, and industrial applications.
On this page, you will find carefully selected Class 10 Physics Chapter 2 Sound MCQs with answers and explanations, along with learning outcomes, quick revision notes, important definitions, formulas, exam tips, and common mistakes to help you prepare effectively for school and board examinations.
Note: In Punjab and Sindh Board textbooks, this topic appears as Chapter 1: Sound. It is presented here as Chapter 2 in the merged Class 10 Physics sequence for your convenience.
Learning Outcomes
After studying this chapter, students will be able to:
- Explain how sound waves are produced.
- Describe the propagation of sound through different media.
- Differentiate between frequency, wavelength, and amplitude.
- Understand pitch, loudness, and quality of sound.
- Explain echo and reverberation.
- Understand the uses of ultrasound.
- Apply formulas related to sound waves.
- Explain practical applications such as sonar.
Quick Notes – Chapter Summary
- Sound is produced by vibrating objects.
- Sound waves require a material medium for propagation.
- Sound travels fastest in solids and slowest in gases.
- Sound waves are longitudinal mechanical waves.
- Frequency determines the pitch of sound.
- Amplitude affects the loudness of sound.
- Human hearing range is approximately 20 Hz to 20,000 Hz.
- Ultrasound has frequencies above 20,000 Hz.
- Echo occurs due to reflection of sound waves.
- Reverberation is caused by repeated reflection of sound.
- Soft materials absorb sound and reduce reverberation.
- Sonar uses reflected sound waves to measure distance.
Important Definitions
Sound: A form of energy produced by vibrating objects that travels through a medium as waves.
Frequency: The number of vibrations or waves produced per second.
Wavelength: The distance between two consecutive similar points of a wave.
Amplitude: The maximum displacement of particles from their mean position.
Pitch: The characteristic of sound that depends on frequency.
Loudness: The perception of sound strength depending mainly on amplitude.
Echo: The repetition of sound caused by reflection from a surface.
Reverberation: Persistence of sound due to multiple reflections.
Ultrasound: Sound waves with frequencies greater than 20,000 Hz.
Sonar: A technology that uses reflected sound waves to detect objects and measure distances.
Important Formulas
Wave Speed Formula
v = fλ
- Where:
- v = Speed of sound
- f = Frequency
- λ = Wavelength
Echo Distance Formula
Distance = (Speed × Time) / 2
Frequency and Time Period
f = 1 / T
- Where:
- f = Frequency
- T = Time period
Important Concepts
Sonar technology.
Production of sound.
Longitudinal waves.
Speed of sound in different media.
Pitch and frequency relationship.
Loudness and amplitude relationship.
Reflection of sound.
Echo formation.
Ultrasound applications.
Class 10 Physics Chapter 2 – Sound MCQs
1. Sound waves are:
- A. Longitudinal mechanical waves ✅
- B. Transverse mechanical waves
- C. Electromagnetic waves
- D. Standing waves only
Explanation: Sound is a longitudinal mechanical wave where particles vibrate parallel to the direction of wave propagation.
2. Which factor does NOT affect the speed of sound in air?
- A. Temperature
- B. Humidity
- C. Loudness ✅
- D. Pressure (when temperature is constant)
Explanation: Loudness is a perception based on amplitude; it does not influence the wave speed in a medium.
3. The speed of sound in air at 20°C is approximately:
- A. 220 m/s
- B. 280 m/s
- C. 343 m/s ✅
- D. 400 m/s
Explanation: At 20°C, sound travels in air at about 343 m/s, depending slightly on humidity.
4. Which property of a sound wave determines its pitch?
- A. Amplitude
- B. Frequency ✅
- C. Wavelength
- D. Wave speed
Explanation: Pitch depends on the frequency — higher frequency means higher pitch.
5. Which sound frequency range can be heard by a normal human ear?
- A. 0 – 100 Hz
- B. 1 – 10,000 Hz
- C. 20 – 20,000 Hz ✅
- D. 50 – 50,000 Hz
Explanation: Humans can hear sounds roughly between 20 Hz and 20 kHz.
6. Ultrasound refers to sound waves with frequencies:
- A. Less than 20 Hz
- B. Between 20 Hz and 20,000 Hz
- C. Greater than 20,000 Hz ✅
- D. Equal to 343 m/s
Explanation: Ultrasound has frequencies higher than the upper limit of human hearing.
7. The time taken for sound to travel to a surface and back is 2 seconds. If the speed of sound is 340 m/s, the distance to the surface is:
- A. 170 m
- B. 340 m ✅
- C. 680 m
- D. 85 m
Explanation: Distance = (speed × time) / 2 = (340 × 2) / 2 = 340 m.
8. Echoes are more distinct when:
- A. The reflecting surface is rough
- B. The reflecting surface is smooth and large ✅
- C. The sound is very loud
- D. The temperature is low
Explanation: A smooth, large surface reflects sound waves better, producing a clear echo.
9. Reverberation in an auditorium can be reduced by:
- A. Using glass walls
- B. Using carpets and curtains ✅
- C. Increasing the sound frequency
- D. Using metallic walls
Explanation: Soft, porous materials absorb sound, reducing reverberation.
10. Which device is used to measure sound intensity levels?
- A. Oscilloscope
- B. Sound level meter ✅
- C. Microphone
- D. Barometer
Explanation: Sound level meters measure sound pressure levels in decibels (dB).
11. The unit of sound intensity level is:
- A. Watt
- B. Decibel (dB) ✅
- C. Hertz (Hz)
- D. Newton
Explanation: Sound intensity level is measured in decibels, a logarithmic scale unit.
12. Which property of sound changes when it travels from air into water?
- A. Frequency
- B. Wavelength ✅
- C. Pitch
- D. Quality
Explanation: Frequency remains constant, but speed changes, so wavelength changes accordingly.
13. Sonar is based on the principle of:
- A. Refraction
- B. Reflection of sound waves ✅
- C. Diffraction
- D. Interference
Explanation: Sonar measures distances by sending sound pulses and detecting their echoes.
14. Which factor increases the speed of sound in air?
- A. Decrease in temperature
- B. Increase in temperature ✅
- C. Lower humidity
- D. Higher altitude
Explanation: Higher temperatures increase the kinetic energy of air molecules, increasing sound speed.
15. The quality of sound is determined by:
- A. Frequency alone
- B. Amplitude alone
- C. Harmonics present in the sound ✅
- D. Wavelength alone
Explanation: The quality or timbre of a sound depends on the number and relative strength of its harmonics.
16. Sound travels fastest through:
- A. Gases
- B. Liquids
- C. Solids ✅
- D. Vacuum
Explanation: Sound travels fastest in solids because particles are closely packed and transfer vibrations quickly.
17. Sound cannot travel through:
- A. Air
- B. Water
- C. Steel
- D. Vacuum ✅
Explanation: Sound requires a material medium for propagation and cannot travel through empty space.
18. The number of vibrations produced per second is called:
- A. Wavelength
- B. Amplitude
- C. Frequency ✅
- D. Velocity
Explanation: Frequency represents the number of complete vibrations or waves produced every second.
19. The loudness of sound mainly depends on:
- A. Frequency
- B. Amplitude ✅
- C. Speed
- D. Wavelength only
Explanation: Larger amplitude means more energy in the wave, producing a louder sound.
20. Which animals commonly use ultrasound for navigation?
- A. Humans
- B. Fish only
- C. Bats ✅
- D. Frogs only
Explanation: Bats use ultrasonic waves and their echoes for navigation and locating prey.
Exam Tips
- Remember the human hearing range (20 Hz – 20,000 Hz).
- Learn the difference between pitch, loudness, and quality.
- Practice numerical questions using v = fλ.
- Understand echo and sonar calculations.
- Remember that sound cannot travel through vacuum.
Common Mistakes
❌ Thinking sound is an electromagnetic wave.
❌ Confusing frequency with amplitude.
❌ Assuming loudness affects speed of sound.
❌ Forgetting that ultrasound is above 20,000 Hz.
❌ Thinking sound travels faster in gases than solids.
Conclusion
Sound explains how vibrations produce waves that transfer energy through different media. Concepts such as frequency, amplitude, pitch, loudness, echo, and ultrasound help students understand both natural phenomena and modern technologies. Learning formulas, important definitions, and practicing MCQs will strengthen understanding and improve performance in Physics examinations.