## Sunday, January 20, 2013

### IX Chapter – Sound: Test Paper by JSUNIL TUTORIAL, BIHAR

JSUNIL TUTORIAL, BIHAR IX CH – SOUND QUESTIONS - 1

(Q)1. Fill in the blanks:

(a) The loudness of sound is proportional to the _________ of the amplitude of the vibration.

(b)The speed of sound __________as it moves from solid to gaseous state.

(c) In any medium the speed of sound __________ with increase in temperature.

(d) The distance between two consecutive compression or two consecutive rarefaction is called the ____.

(e) The change in the density or pressure from a maximum value to minimum and then back to the maximum is called an ___________.

(f) The number of periodic oscillations per unit time is called the ________ of the sound wave.

(g) Sound is produced due to ________of different objects.

(h). Sound travels as a _________ wave through a material medium.

(i) Sound travels as successive _________ and ___________ in the medium.

2. Q. A person has a hearing range from 20 Hz to 20 kHz. What are the typical wavelengths of sound waves in air corresponding to these two frequencies? Take the speed of sound in air as 344 m/s.

3. Q. The frequency of a source of sound is 100 Hz. How many times does it vibrate in a minute?

4. Q. Explain how bats use ultrasound to reach a prey.

5. Q. A sonar device on a submarine sends out a signal and receives an echo 5 s later. Calculate the speed of sound in water if the distance of the object from sub-marine is 3,625 m.

6. Q. A sound wave travels at a speed of 339 ms–1. If its wavelength is 1.5 cm, what is the frequency of the wave? Will it be audible?

7. Q. A stone is dropped from the top of a tower 500 m high into a pond of water at the base of the tower. When is the splash heard at the top ? Given, g = 10 ms–2 and speed of sound = 340 m/s.

8. Q. Which type of waves is produced when a stone is dropped on the surface of water in a pond ?

9. Q. What kind of waves are produced when a spring is pulled in the downward direction and released?

10. Q. What is the nature of electromagnetic waves?

11 Q.Give three important characteristics of wave motion.

12.Q. Differentiate between a periodic wave and a pulse. [http://jsuniltutorial.weebly.com/]

13.Q. Explain how ultrasounds help to detect cracks and flaws in metal blocks.

14.Q. Define time period of sound wave. What is its SI unit? How is it related with frequency?

15. Q. Explain, how compression and rarefaction are produced in air near a source of sound.

JSUNIL TUTORIAL, BIHAR IX CH – SOUND QUESTIONS -2
1 Mark Questions
Q1. Which sound has a higher pitch, guitar or car horn?

Q2. Name three animals which can hear ultrasonic vibrations.

Q3. How are the wavelength and frequency of a sound related to its speed?

Q4. Why sound wave is called a longitudinal wave?

Q5. Frequency of a source of sound is 100 Hz. How many times does it vibrate in a minute?

Q6. What is an echo?

Q7.What do waves transport - matter or energy?

Q8. What is a wave?

Q9. Which characteristics of the sound help us to identify a person by his voice if he is sitting in a dark room?

Q10. If the amplitude of a wave is doubled, what will be the effect on its loudness?

2 Marks Questions

Q11. Which wave property determines a) loudness, b) Pitch?

Q12. Why are the ceilings of concert halls curved?

Q13. How is ultrasound used for cleaning?

Q14. Sound is produced due to a vibratory motion, then why a vibrating pendulum does not produce sound?

Q15. A sound produces 20 crests and 20 troughs in 0.4 sec. Find the frequency of the wave.

Q16. Why sound waves are called mechanical waves?

3 Marks Questions

Q17. How is sound produced in school bell?

Q18. Bats have no eyes then how do they catch their prey?

Q19. What is SONAR?

Q20. Write three uses of multiple reflection of sound.

3 Marks Questions (Numerical)

Q21. Calculate the wavelength of a sound whose frequency is 220 Hz and speed is 440 in a given medium.

Q22. A body is vibrating 6000 times is 1 minute. If the velocity of sound in air is 360 m/s, find

(i) Frequency in Hz (ii) wavelength of sound.

Q23. A stone is dropped from a 500 m tall building into a pond. When is sound splash heard? Given g=10 m/s2 , speed of sound = 340 m/s.

Q24. An echo is heard in 3 sec after the emission of sound. If speed of sound in air is 342 m/s, what is the distance of the reflecting surface from the source?

M.C.Q. (1 Mark each)

Q25. For reflection of sound wave, we need -

A. A polished mirror B. A large size, opaque reflecting surface C. A concave surface D. A glass plate

Q26. The speed of sound in air is -

A. Less than in solids & liquids B. Same as that in solids & liquids

C. Greater than in solids and liquids D. None of these

Q27. We can sense a compression in a spring if

A. Turns are close together B. Neither closes nor apart C. Turns are further apart than normal D. None of these

Q28. When sound is allowed to fall normally on the reflecting surface, the angle at which the intensity of sound will be maximum is: A. 600 B. 900 C. 300 D. 00

Q29. The mechanical wave is A. Sound Wave B. Microwave C. Radio Wave D. Light Wave

Q30. Sound wave cannot pass through A. Metals B. Water C. Air D. Vacuum

Q31. The persistence of sound is an auditorium is the results of

A. Single reflection of sound B. Repeated reflection of sound

C. Repeated refraction of sound D. Vibration of object placed in an auditorium

Q32.A wave set up a single disturbance of short duration is called

A. pulse B. Sound Wave C. Wave D. None of these

Q33. To determine the velocity of a pulse propagated through a stretched slinky

A. A slight jerk is given to the slinky B. No jerk is given to the slinky

C. Sharp jerk is given to the slinky D. None of these.

Q34. The distance x in below diagram is-

A. B. 2 C. 3 /2 D. /2

Q35. Two sounds of same pitch and loudness differ in

A. Tone B. Note C. Quality D. All of these

JSUNIL TUTORIAL, BIHAR IX CH – SOUND QUESTIONS - 3

Q 1 What is a wave?

Q 2 Explain why the ceilings of concert halls and conference halls made curved?

Q 3 What is law of reflection in sound?

Q 4 Priya clapped her hand near a cliff and heard the echo after 5 second. If the speed of sound be 330m/sec, then find the distance of the cliff from priya?

Q 5 What are infrasonic and ultrasonic?

Q 6 Calculate the time in which a tuning fork of frequency 234 Hz completes 26 vibrations.

Q 7 We hear thunder sound a few seconds after the flash is seen even though they occur simultaneously. Why?

Q 8 A sound wave has a frequency of 1500Hz and wavelength 25cm. How long will it take to travel 3 km?

Q 9 Why and how is reverberation removed in an auditorium or a big hall?

Q 25 State Laws of Reflection of Sound

Q 10 Harry standing 440 m away from a wall fired a gun and heard its echo 2 s later. How is an echo formed? Calculate the velocity of sound in air.

Q 11 How does sound reaches our ears?

Q 12. What will happen to the loudness of a sound wave if its amplitude is doubled? Name a unit of sound. Is loudness affected by change in frequency?

Q. 13. How do sound waves propagate?

Q. 14. Are the particles of the medium dragged along with the wave as sound wave propagates through the medium? In which medium—solid, liquid or gas, does the sound wave travel fastest?

Q 15 Find the distance travelled by a sound wave of frequency 20 KHz, wavelength 1.7 cm in 10 s.

Q 16 Define frequency of a sound wave. What is its SI unit and how is it related to pitch?

Q 17 What do you understand by frequency of a sound wave? What is the relationship between velocity of sound wave and its frequency?

Q 18 Explain that sound is a mechanical wave. How do sound waves travel in different media? What is the approximate speed of sound in air?

Q 19 What is the relevance of amplitude and of frequency of a vibrating body to sound produced by it?

Q 20 Define echo. A sonar echo takes 2.2s to return from a whale. Find the distance of the whale below the surface of the water. [Given the speed of sound in sea water at 250C = 1533m/s]

Q 21 Define the terms. 1. Audible range of normal human ear 2. Ultrasonics 3. Infrasonics

When vibration is a necessary condition for production of sound, then why the vibrating pendulum does not produce sound?

Q 22 Define speed of sound. Name the factors on which the speed of sound depends. Why the intensity of sound of a speaker is larger immediately after rain?

Q 23 Explain The structure of human ear.

Q 24 What is an echo? Calculate the minimum distance in air required from a surface reflecting sound to hear an echo at 200C.

Q 25 What is SONAR stands for? For what purpose it is used?

Q 26 Explain how defects in a metal block can be detected using ultrasound.

Q 27 What is the frequency of an oscillating body? The frequency of a source is 80Hz. Find the number of times it vibrates in a minute.

Q 28 Explain the working and applications of SONAR.

Q 29 Rajan and Mohan are standing at opposite ends of an aluminium rod. Rajan strikes the end of the rod with a stone. Calculate the ratio of times taken by the sound waves in air and in aluminium to reach Mohan. [Velocity in aluminum = 6420m/s]

Q 30 Explain the statement ‘Wave transfers energy and not the matter’ with the help of an activity

JSUNIL TUTORIAL, BIHAR IX CH – SOUND QUESTIONS -4

Q 1 Frequency of a wave motion is 250 Hz. What is its time period?

Q 2. What do you mean by an Oscillation of a sound wave?

Q 3 Derive a relation between speed, frequency and wavelength of a sound wave?

Q 4 A sound wave has a frequency of 2 kHz and wavelength 40 cm. Calculate its speed?

Q 5 Calculate the wavelength of a sound wave whose frequency is 220 Hz and speed is 440 m/s in a given medium?

Q 6 Calculate a) the wavelength b) the time period of a tuning fork of frequency 512 Hz that is set to vibrate. Velocity of sound in air is 320 m/s.

Q 7 What is the wavelength of sound waves produced in air by a vibrating tuning fork whose frequency is 256 Hz when the velocity of sound in air is 330 m/s ?

Q 8 Why the flash of lightning due to collision of clouds is seen much before the thunder, although both occur simultaneously?

Q 9 What do you understand by speed of sound? How does it depend upon the medium and temperature?

Q 10 What is reflection of sound? Explain the laws of reflection with respect to sound?

Q 11 What is Echo. Explain the conditions that have to be satisfied to hear an echo?

Q 12 Why do echoes produced in an empty auditorium usually decrease when it is full of audience?

Q 13 What is reverberation?

Q 14 A girl clapped his hands near a cliff and heard the echo after 5 s. What is the distance of the cliff from the person if the speed of the sound, velocity of sound in air is taken as 346 m/s?

Q 15 A boy fires a gun and hears the echo 2 seconds later. If he is 480 m away from a wall, calculate the velocity of sound in air?

Q 16 Explain the term audible range, Infrasonic frequencies, Ultrasonic frequencies?

Q 17 Explain how is the principle of echo used by

(a) The bat during its flight at night. (b) The dolphin to locate small fish as its prey.

Q 18 Figure shows a waveform of frequency 50 Hz in a string. The numbers in the string represent distance in centimeter. For this wave motion, find: (a) wavelength (b) amplitude,

Q.19. What should be the minimum distance between a sound source and reflector for a distinct echo?

Q.20. Which part of the ear turns pressure variations into electrical signals?

Solution
Sound solved Numerical Test Paper-1
Class 09 Sound solved CBSE Test Paper-2
Class 09 Sound solved CBSE Test Paper-3
Class 09 Sound solved CBSE Test Paper-4

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