Study of Sound
Q1. What is sound?
A. Sound is a form of energy produced by vibrating objects.
Q2. How does sound travel?
A. Sound travels in the form of longitudinal waves through a medium.
Q3. Can sound travel in vacuum?
A. No, sound needs a material medium to travel.
Q4. What are longitudinal waves?
A. Waves in which particles of the medium vibrate parallel to the direction of wave propagation.
Q5. What are compressions in a sound wave?
A. Regions of high pressure and particle density in a sound wave.
Q6. What are rarefactions?
A. Regions of low pressure and particle density in a sound wave.
Q7. What is the speed of sound in air at 25°C?
A. Approximately 346 m/s.
Q8. Name factors affecting the speed of sound.
A. Nature of medium, temperature, pressure, and humidity.
Q9. What is frequency?
A. The number of vibrations per second, measured in Hertz (Hz).
Q10. What is the audible range for humans?
A. From 20 Hz to 20,000 Hz.
Q11. What are ultrasonic waves?
A. Sound waves with frequency greater than 20,000 Hz.
Q12. Name one use of ultrasonic waves.
A. Used in medical scanning (ultrasonography).
Q13. What are infrasonic waves?
A. Sound waves with frequency less than 20 Hz.
Q14. Give one example of infrasonic sound.
A. Elephants produce infrasonic sounds for long-distance communication.
Q15. What is amplitude in sound waves?
A. The maximum displacement of particles from their mean position.
Q16. What does amplitude determine?
A. The loudness of the sound.
Q17. What is pitch?
A. The perception of how high or low a sound is, determined by its frequency.
Q18. What is the time period of a wave?
A. The time taken for one complete vibration, T = 1/f.
Q19. State the relationship between wave speed, frequency, and wavelength.
A. v = f × λ, where v is speed, f is frequency, and λ is wavelength.
Q20. What is an echo?
A. Reflection of sound from a surface heard after the original sound.
Q21. What is the minimum distance for hearing an echo?
A. About 17 meters in air.
Q22. What is reverberation?
A. Persistence of sound due to multiple reflections.
Q23. How can reverberation be reduced?
A. By using soft materials like curtains, carpets, and acoustic panels.
Q24. What is SONAR?
A. Sound Navigation and Ranging – used to measure depth of water and detect objects underwater.
Q25. What is the principle of SONAR?
A. Echo-ranging using ultrasonic waves.
Q26. Name one application of SONAR.
A. Detecting submarines.
Q27. What is resonance?
A. The phenomenon in which a vibrating object causes another object to vibrate at its natural frequency.
Q28. What is the unit of sound intensity?
A. Decibel (dB).
Q29. Why does sound travel faster in solids than in gases?
A. Because particles in solids are more closely packed, allowing faster transmission of vibrations.
Q30. Give one harmful effect of noise pollution.
A. Prolonged exposure to loud noise can cause hearing loss.