Formatting page ...
CHAPTER 7 : SOUND PA RT A 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. What do you mean by the terms infrasonic, audible range and ultrasonic? With reference to the wave define the terms (i) amplitude (ii) time period (iii) frequency and (iv) wavelength. Write the relation between wave velocity V, frequency f and wavelength . How the frequency f of a wave is related to the time period T? What type of sound wave is? Write its types. Write the difference between: (i) longitudinal and transverse waves. (ii) Mechanical (or elastic) and electromagnetic waves (iii) light waves and electromagnetic waves. On what factors the speed of a sound in a medium depends? On what factors the speed of transverse wave in a stretched string depends. When a wave travelling in one medium to another, which among the following change does not change: speed, wavelength, intensity and frequency of the wave? What do you mean by reflection of sound wave? What is the only requirement for the reflection of sound wave? What do you mean by Echo? Write the condition for the formation of echo. Write the conditions for hearing echo distinctly. Write the formula to find the velocity (speed) of sound by the method of echo. Write the two applications of echoes. Name the waves usually used in this method. What is its frequency range? Is it audible to us if not why? What is meant by sound ranging? Give one use of sound ranging. Name the waves are used in the sound ranging and echo depth sounding and why? Why are the waves mentioned by you is not audible to us? Explain the use of (echo) ultrasonic waves in the case of bats, dolphins and fisherman. What do you mean by : (i) Sound ranging and (ii) Echo depth sounding. Expand : (i) SONAR and (ii) RADAR. State the principle on which these are based. Name the waves used in these. Write the application of these. Write the application of ultrasonic waves in medical field (OR) What is the use of echo in medical field? PART-B 1. 2. 3. Define free vibrations of a body. State one condition for a body to execute free vibrations. What do you mean by : (i) free (natural) period (ii) natural frequency of vibration of a body? Name two factors on which natural frequency of vibration of a body depends. Draw a graph between displacement from mean position and time for a body executing free vibrations in vacuum. 4. On what factor the frequency of a oscillating pendulum depends. 1 2 g l 5. On what factor the frequency of oscillating a load suspended from a string depends. { 6. When an air column in a flute ( or organ pipe ) is made to vibrate, it vibrates with its natural frequency. How the frequency of this depends on the length of the air column? What is the ratio of the frequency of the organ pipe when it is: (i) open at both ends (ii) one end is closed? What are the factors on which the frequency of a string instruments depends? (OR) State the three ways of increasing the 7. 8. frequency of a stretched string { hint : f = [ ]} { hint : f = [ ]} [ ]} hint : f = 2 m k 1 T 2 l r 2 d 9. What adjustments would you make for tuning a stringed instruments for it to emit a note of a desired frequency? 10. The diagram given shows three ways in which the string of length l in an instrument can vibrate (i) Which of the diagram shows the principal note? (ii) Which vibration is of long wavelength? (iii) Which of the vibration is having least wavelength and longest wavelength? (iv) Which of the vibration is having least frequency and highest frequency? (v) Compare the frequency and wavelength of (ii) and (iii) 11. Explain of stings of different thickness are provided on a stringed instruments. 12. What is the frequency of the stretched string when it is fixed at both the ends and plucked at half , one-fourth, one-sixth etc distance from the fixed position? 13. What are damped vibrations? Draw a displacement-time graph for damped vibrations. How do they differ from free vibrations? Give one example. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26. 27. 28. 29. A tuning fork is sent into vibrations in air. Name the kind of vibrations it executed. Differentiate between free vibrations and damped vibrations. What are forced vibrations? Give an example to illustrate your answer. Observe the diagram and answer the questions given (i) Name the kind of vibrations (ii) give an example of such vibrations (iii) why is the amplitude of vibrations gradually decreasing? (i) Name the kind of vibrations (ii) give an example of such vibrations (iii) why is the amplitude of vibrations not decreasing? Distinguish between the free (or natural) and forced vibrations. What is meant by resonance? State the condition for the occurrence of resonance. Differentiate between forced and resonant vibrations. Why is a loud sound heard at resonance? When the stem of vibrating tuning fork is pressed against the top of a cable, to loud sound is heard. Why? The stringed instruments provided with a hollow sound box with a hollow sound box. Why? Observe the diagrams and answer the following questions. The diagram given below shows In the figure A, B, C and D are four two identical tuning forks A and B pendulums suspended from the same of the same frequency mounted on elastic string XY. Lengths of separate sound boxes with their pendulum A and D are equal, while open ends facing each other. The the lengths of pendulum B is shorter fork A is sent into vibration. (i) and of the pendulum C is longer. The describe your observation (ii) state pendulum A is set into vibration. (i) the principle illustrated by this What is your observation? (b) Give experiment reason for your observation. A vibrating tuning fork, held over an air column of a given length with its one closed, produces a loud audible sound. Name the phenomenon responsible for it and explain the observation. Observe the diagram and answers the questions given. In the given figure A, B, C and D represent test tubes each of length 20 cm which are filled with water up to heights of 12 cm, 14 cm 16 cm and 18 cm respectively. If a vibrating tuning fork is placed over the mouth of test tube D, aloud sound is heard. (i) Describe the observations with the tubes A, B and C when the vibrating tuning fork is placed the mouth of these tubes. (ii) Give the reason for your observation in each case. (iii) Sate the principle illustrated by the experiment. When a troop crosses a suspension bridge the soldiers are asked to break steps. Explain the reason. How do you tune your radio set to a particular station? Name the phenomenon involved in doing so and define it. At a particular speed of the vehicle some parts of the machine parts vibrate vigorously and a rattling sound is heard. Why? What can be done to change this? PART-C 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. Name the three characteristics of a musical sound. On what factors the characteristics of a sound depend. Define loudness. On what factors it depends. State the dependence of loudness on the factors stated by you. What do you understand by intensity? What is the unit of intensity? On what factors the intensity of a sound wave depends? On what factors the loudness of a sound depends. Differentiate loudness and intensity of a sound. Write the relation between loudness and intensity . Write the unit of loudness and level of sound. If the amplitude of a wave is doubled, what will be the effect of its loudness? Identify the loud sound and state the reason for your answer (OR) How does the pattern of loud note differ from a soft note. 11. 12. 13. 14. 15. 16. 17. 18. 19. Two waves of the same pitch have amplitude in the ratio 1:3. What will be the ratio of their (i) loudness (ii) Frequencies? Why is the loudness of a sound heard by a plucked wire increased when it is mounted on a soft board? Comment on the statement loudness of a sound is a subjective quantity, while intensity is an objective quantity . What is the safe limit of sound level in dB for our ears? Want is meant by noise pollution? Name the source of sound causing noise pollution. Define pitch (Or shrillness) . On what factors the pitch of a sound depend? What determines the pitch of a sound? Name the subjective property of a sound related to its frequency. Identify the waves of different pitch and state the reason for your answer (OR) draw a diagram to show the pattern of high pitch note and a low pitch note, but of the same loudness. 20. Name and define the characteristic which enables one to distinguish two sounds of same loudness, but of different frequencies, given by the same instrument. 21. How is it possible to detect the filling of a bottle under a water tap by hearing the sound at a distance? 22. The frequencies of a high notes given by flute, guitar and a trumpet are respectively 400 Hz, 200 Hz and 500 Hz. Which one of these has the highest pitch? 23. Observe the diagram and answer (i) Which vibration will produce loud sound and why? (ii)The sound of which wave have maximum shrillness and why? (iii) What is the ratio of wavelength of vibration (a) and (c)? 24. Name the characteristic which enable one to distinguish the sound of the two musical instruments even if they are of the same pitch and same loudness. 25. Explain the subjective nature of pitch and objective nature of frequency. 26. How do the two sounds of same loudness and the same pitch produced by different instruments differ? Draw diagrams to show your answer. 27. Two identical guitars are played by two persons to give notes of the same pitch. Will they differ in quality? Give a reason for your answer. 28. We can easily distinguish between the sounds of a piano and a flute without seeing. Explain. 29. Observe the diagram and answer the questions Two musical notes of the same pitch and same loudness are played on two different instruments. Their wave patterns are shown. Explain why the wave patterns are different. 30. How is it possible to recognize a person by his voice without seeing him? 31. State the factors that determine (i) the pitch of a note (ii) the loudness of the sound heard (iii) the quality of the note (OR) name the characteristic of the sound affected due to a change in its (i) amplitude (ii)waveform (iii) frequency. 32. In what respect does the wave pattern of a noise and a music differ? Draw diagram to show your answer. 33. Observe the diagram and answer the question. The sketches I to IV shows the sound waves all formed in the same time interval. Which diagram shows (i) a note from a musical instrument (ii) a soft (not loud) note (iii) a bass ( low frequency) note 34. Observe the diagram and answer the question. A microphone is connected to the Y-input of a C.R.O. Three different sounds are made in turn in front of the microphone. Their traces (a) (b) and (c) produced on the screen as shown. (i) Which trace is due to the loudest sound? Give reason for your answer (ii) Which trace is due for the sound with the lowest pitch? Explain your answer. 35. State the differences between a musical note and a loud note.
|
