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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.
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