MP Board Solutions Class 9 Science Chapter 11 – Sound
MP Board Solutions for Class 9 Science Chapter 11 – Sound are essential for understanding key Physics concepts in the MPBSE curriculum. These well-structured answers help students grasp topics like the production, propagation, and reflection of sound, along with frequency, pitch, and the speed of sound. Designed as per the latest syllabus, these solutions strengthen conceptual clarity and improve exam preparation. Ideal for revision and practice, they encourage logical thinking and scientific understanding, making them a valuable study tool for scoring well in Class 9 Science exams.
MP Board Solutions Class 9 Science – Sound – Exercise Images
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Sound – Important Questions with Answers
1. Define sound.
Answer: Energy perceived by ears when particles vibrate.
2. How is sound produced?
Answer: By vibrating objects.
3. Sound in air is what type of wave?
Answer: Longitudinal wave.
4. Can sound travel through vacuum?
Answer: No, needs matter to propagate.
5. Approx speed of sound in air.
Answer: ~343 m/s.
6. In which medium does sound travel fastest?
Answer: Solids.
7. SI unit of frequency.
Answer: Hertz (Hz).
8. Define amplitude.
Answer: Maximum displacement from mean position.
9. Define frequency.
Answer: Number of oscillations per second.
10. Define time period.
Answer: Time for one complete vibration.
11. Relation between frequency and time period?
Answer: f = 1/T.
12. Define wavelength of sound.
Answer: Distance between two compressions or rarefactions.
13. Formula for wave speed.
Answer: v = λ × f.
14. What are ultrasonic waves?
Answer: Frequency > 20 kHz.
15. Infrasonic waves?
Answer: Frequency < 20 Hz.
16. Audible range for humans.
Answer: 20 Hz to 20 kHz.
17. Give example of animal that hears ultrasonic.
Answer: Bats.
18. Role of the eardrum.
Answer: Vibrates hearing sound; transmits to inner ear.
19. What is echo?
Answer: Sound reflection heard after delay.
20. Minimum distance to hear echo?
Answer: ~17.2 m at normal conditions.
21. What is SONAR?
Answer: Technique using sound reflection to detect objects underwater.
22. Define reverberation.
Answer: Persistence of sound due to repeated reflections.
23. How to reduce reverberation?
Answer: Use sound-absorbing materials (curtains, carpets).
24. What is pitch?
Answer: Highness or lowness of sound, depends on frequency.
25. How does sound enable communication?
Answer: Vibration-generated waves carry information between people.
Sound explains how vibrations produce sound and how it travels through different media. Key concepts like frequency, amplitude, pitch, and echo are discussed with applications in communication, musical instruments, and animal behavior. The chapter also explains how the human ear detects sound. This understanding connects science with daily life—from cultural music to safety devices in farms and schools.
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