The chapter "Sound" in Class 9 Physics is a cornerstone for understanding wave phenomena, a fundamental concept that extends into higher classes and various scientific fields. It delves into how sound is produced, propagates, and is perceived, introducing crucial wave characteristics like frequency, wavelength, and amplitude. A strong grasp of this chapter is essential for building a solid foundation in physics.
From an examination perspective, "Sound" is consistently featured in CBSE board exams. Questions range from direct definitions and conceptual understandings to numerical problems involving wave speed, frequency, and wavelength, as well as application-based scenarios like echoes and ultrasound. Excelling in this chapter ensures not only high scores in Class 9 but also prepares students for related topics in Class 11 and 12, making it a high-yield area of study.
30
Minutes
30
Questions
4 / -1
Marking
Q1. Sound waves are an example of:
Transverse waves
Longitudinal waves
Electromagnetic waves
Both transverse and longitudinal waves
Q2. Which of the following is necessary for the propagation of sound?
Vacuum
Medium
Light
Magnetic field
Q3. The unit of frequency is:
Metre (m)
Second (s)
Hertz (Hz)
Metre per second (m/s)
Q4. The maximum displacement of particles of the medium from their mean position is called:
Wavelength
Frequency
Amplitude
Time period
Q5. Which of the following characteristics of a sound wave determines its loudness?
Frequency
Wavelength
Amplitude
Time period
Q6. The speed of sound is maximum in:
Gases
Liquids
Solids
Vacuum
Q7. An echo is heard when the minimum distance between the source of sound and the reflecting surface is approximately:
3.4 m
17.2 m
34.4 m
68.8 m
Q8. The phenomenon of persistence of sound in a large hall due to repeated reflections is called:
Echo
Resonance
Reverberation
Refraction
Q9. Bats use which of the following to navigate and find prey?
Infrasound
Ultrasound
Audible sound
Electromagnetic waves
Q10. If a wave completes 20 oscillations in 5 seconds, its frequency is:
4 Hz
10 Hz
100 Hz
0.25 Hz
Q11. The range of frequencies audible to the human ear is approximately:
Below 20 Hz
20 Hz to 20,000 Hz
Above 20,000 Hz
2 Hz to 200 Hz
Q12. A sound wave has a frequency of 2 kHz and a wavelength of 35 cm. How long will it take to travel 1.5 km?
2.1 s
3.0 s
1.5 s
4.3 s
Q13. Which of the following statements is true about sound waves?
They can be polarized.
They travel faster in vacuum than in air.
They are mechanical waves.
They are electromagnetic in nature.
Q14. If the amplitude of a sound wave is doubled, its loudness will become:
Half
Double
Four times
One-fourth
Q15. A sonar device on a submarine sends out a signal and receives an echo 5 seconds later. If the speed of sound in water is , what is the distance of the object from the submarine?
7500 m
3750 m
15000 m
750 m
...and 15 more challenging questions available in the interactive simulator.