Class 9 Science Chapter 11 Sound – One Liner Questions and Answers | Notes Learn CBSE Class 9 Science Chapter 11 Sound with important one-liner questions and answers. Quick revision notes covering production of sound, propagation, echo, ultrasound, and applications.
Q1. What is sound?
Ans. Sound is a form of energy which produces a sensation of hearing in our ears.
Q2. How is sound produced?
Ans. Sound is produced by the vibration of objects.
Q3. What is required for the propagation of sound?
Ans. A material medium like solid, liquid, or gas is required for the propagation of sound.
Q4. Can sound travel through vacuum?
Ans. No, sound cannot travel through vacuum.
Q5. What is a mechanical wave?
Ans. A mechanical wave is a disturbance that moves through a medium by particle vibration.
Q6. What are compressions and rarefactions?
Ans. Compressions are regions of high pressure and rarefactions are regions of low pressure.
Q7. What type of wave is a sound wave?
Ans. Sound waves are longitudinal waves.
Q8. Define wavelength.
Ans. The distance between two consecutive compressions or rarefactions is called wavelength.
Q9. What is the SI unit of wavelength?
Ans. The SI unit of wavelength is metre (m).
Q10. Define frequency.
Ans. Frequency is the number of complete oscillations per second.
Q11. What is the SI unit of frequency?
Ans. The SI unit of frequency is hertz (Hz).
Q12. Define time period of a sound wave.
Ans. Time period is the time taken for one complete oscillation.
Q13. How are frequency and time period related?
Ans. Frequency (v) = 1 / Time period (T).
Q14. What determines the pitch of a sound?
Ans. Pitch is determined by the frequency of the sound wave.
Q15. What determines the loudness of a sound?
Ans. Loudness depends on the amplitude of the sound wave.
Q16. What is amplitude?
Ans. Amplitude is the maximum displacement of particles from their mean position.
Q17. What is the speed of sound in air at 25°C?
Ans. The speed of sound in air at 25°C is approximately 346 m/s.
Q18. In which medium does sound travel the fastest: air, water, or iron?
Ans. Sound travels fastest in iron.
Q19. What is an echo?
Ans. Echo is the reflection of sound that is heard after the original sound.
Q20. What is the minimum distance required to hear an echo?
Ans. At least 17.2 meters.
Q21. What is reverberation?
Ans. Reverberation is the persistence of sound due to multiple reflections.
Q22. How can reverberation be reduced in halls?
Ans. By using sound-absorbing materials like draperies and carpets.
Q23. What is the audible range of human hearing?
Ans. 20 Hz to 20,000 Hz.
Q24. What are sounds with frequency less than 20 Hz called?
Ans. Infrasonic sounds.
Q25. What are sounds with frequency more than 20,000 Hz called?
Ans. Ultrasonic sounds.
Q26. Name two animals that produce ultrasonic sounds.
Ans. Bats and dolphins.
Q27. Mention one application of ultrasound in the medical field.
Ans. Ultrasound is used for imaging internal organs like the liver and kidney.
Q28. What device helps hearing-impaired people hear sounds better?
Ans. Hearing aid.
Q29. How are flaws in metal blocks detected?
Ans. By using ultrasonic waves.
Q30. What is the relation between speed, frequency, and wavelength of sound?
Ans. Speed = Wavelength × Frequency (v = λν).
Class 9 Science Sound Notes
Sound One Liner Questions Class 9
CBSE Class 9 Chapter 11 Questions
Production of Sound Class 9
Echo and Ultrasound Class 9