DIFFERENT KINDS OF SOUNDS /If 



QUESTIONS 



1. Compare solids, liquids, and gases as media for trans- 

 mitting sound waves. State any common examples which you 

 have noticed, showing how some substances are better media 

 than others. 



2. How fast does a wave travel through air ? How far would 

 a wave go in one minute ? 



3. Explain the conditions necessary to produce an echo. Why 

 is an echo generally heard better at night? Why better on 

 water? 



4. What is a reverberation ? Why do we not hear much rever- 

 beration in a hall full of people ? 



5. How are forced and sympathetic vibrations caused? Explain 

 the difference between them. 



6. What is a resonator? How do resonators serve to make 

 sounds seem louder? 



7. Name different bodies which may act as resonators. Show 

 the value of resonators in musical instruments, naming several 

 instruments and the sort of resonator they use. 



8. Explain the action of a megaphone. For what is it used ? 



SECTION III 

 DIFFERENT KINDS OF SOUNDS 



114. Tones. It must be kept in mind that the vibra- 

 tions which cause sound waves are not only very small 

 but usually very rapid in some cases there are several 

 thousand every second. Each of these vibrations causes 

 one wave in the air, which moves away so fast as to be 

 1125 feet distant at the end of one second. But as the 

 body keeps vibrating, and as each to-and-fro motion 

 causes one wave, it is clear that at the end of one 

 second the air from the body to a point 1125 feet away 



