Chapter 12 of 18
Revision Notes
Study of Sound — Revision Notes
Maharashtra Board · Class 9 · Science
Study of Sound revision notes for Maharashtra Board Class 9 Science: 4 topics in quick points. Part of the Maharashtra Board Class 9 Science syllabus.
45 questions28 flashcards5 concepts
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Key Topics to Revise
1
Nature of Sound and Sound Waves
- Sound is a form of energy that travels in the form of waves
- Sound requires a medium for propagation - it cannot travel through vacuum
- Sound waves are longitudinal waves where particles oscillate parallel to the direction of wave propagation
2
Velocity of Sound
- Velocity of sound is highest in solids, medium in liquids, and lowest in gases
- At 25°C: Steel (~6000 m/s), Water (~1500 m/s), Air (346 m/s)
- Velocity increases with increase in temperature of the medium
3
Audible, Infrasound and Ultrasound
- Human hearing range: 20 Hz to 20,000 Hz (20 kHz) - called audible sound
- Infrasound: frequency less than 20 Hz (e.g., earthquake vibrations, pendulum)
- Ultrasound: frequency greater than 20 kHz
4
Applications of Ultrasound
- Communication between ships at sea
- Joining plastic surfaces together
- Sterilizing liquids like milk by killing bacteria
Get complete notes with diagrams and examples
Full NotesKey Concepts
Sound is a form of energySound waves have wavelength (λ)Sound travels at different speedsAudible sound (20 Hz to 20Sound waves follow laws of reflection
Frequently Asked Questions
What are the important topics in Study of Sound for Maharashtra Board Class 9 Science?
Key topics in Study of Sound include Nature of Sound and Sound Waves, Velocity of Sound, Audible, Infrasound and Ultrasound, Applications of Ultrasound. Study these first, then practise questions on each for Class 9 exams.
How should I revise Study of Sound for Class 9 exams?
Learn the core ideas first, then work through the 45 practice questions on Study of Sound. Revise definitions regularly and use flashcards for quick recall before the exam.
Sources & Official References
Content is aligned to the official syllabus. Refer to the board website for the latest curriculum.
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