(a) Mention two practical applications of reflection of sound waves.

(b) How is the pressure variation in a sound wave amplified in human ear ?

© In a ripple tank, ten ripples are produced per second. If the distance between a trough and a neighbouring crest is 12 cm, calculate the frequency, wavelength and velocity of the wave.

(a) Megaphone, stethoscope.

(b) The pressure variation in the human ear is amplified by three bones anvil, hammer, stirrup.

© Frequency =10 Hertz.

Distance between adjacent crest and trough = 12 cm.

Wavelength = Distance between adjacent crests = 12 + 12 = 24 cm.

Velocity = Wavelength x Frequency = 24 x 10 = 240 cm s^-1.