(a) amplitude
   (b) vibration
   (c) frequency
   (d) phase
Ans: (a)
211. The device used to record the sound is
   (a) a microphone
   (b) a headphone
   (c) a phonograph
   (d) an amplifier
Ans: (c)
212. One can be recognised by his voice alone due to the factor of
   (a) quality
   (b) amplitude
   (c) pitch
   (d) loudness
Ans: (a)
213. A timer in a race is at the finish line. He should start his stop watch
   (a) as soon as he hears the report of the gun
   (b) the moment he sees the flash
   (c) either (a) or (b) since that makes no difference
   (d) None of the above
Ans: (b)
214. Echoes are produced by
   (a) the reflection of sound waves
   (b) the refraction of sound waves
   (c) the interference of sound waves
   (d) reverberation of sound waves
Ans: (a)
215. The stem of a vibrating tuning fork is pressed against a sound box. Then
   (a) the loudness of the sound increases
   (b) the loudness remains the same