We hear when sound enters the Spiral channel . The sound then moves
to the
and causes it to vibrate. Three delicate bones, the
, and
_transfer the vibrations to the
The fluid in the ear
canal of the eardnim _ vibrates and
creates waves. nerves
along the channel respond and move tiny
_frequencies are heard at the wider opening of the
channel, and higher frequencies are heard in the narrower part of the

speed of light in vacuum is 300,000 km/s

speed of light in other mediums is given by the expression v = c/n, where c is the speed of light in vacuum and n is the refractive index of medium.

for the first medium v = 200,000 km/s

  so, refractive index of medium = 300000/200000 = 1.5

    1.5 refractive index is usually for glass. so first medium is glass.

for the second medium v = 250,00 km/s

so, refractive index of medium = 300000/250000 = 1.2

    1.2 refractive index is usually for water. so second medium is water.

for the third medium v = 0 km/s

so, refractive index of medium = 300000/0 = ∞

    ∞ refractive index is usually for opaque mediums. so third medium is opaque medium.

third one with arrows on top of each other going the same direction