SOUND

       HOME WORK-  21.01.2017  

CLASS IX 

 UNIT : SOUND

1.      Differentiate between  (i) low pitch and high pitch sound  (ii) loud sound and soft sound

2.      A Sonar device sends out a signal in water and receives an echo in 5 seconds. If the speed of sound in water is three times that in air find the depth of ocean at that point

3.      Give any two differences between longitudinal waves and transverse waves with examples

4.      State the condition for an echo to be heard

5.      What is reverberation  How does it differ from echo   How can it be reduced

6.      Explain with necessary fig the structure of human ear and the function of each part

7.      What is audible range Also state how speed of sound vary with  (i) temperature (ii) pressure  (iii)medium

8.      What are ultrasonics and infrasonics How are they used in various practical situations

9.      What are the characteristics by which human ear interpret a sound

10.  Define the terms loudness ,intensity, note and tone