A low-flving jet aircraft approaches a stationary observer on the ground at a speed of 1000 km/hr on a day when the speed of sound is 345 m/s. (a) If the engine emits a sound of frequency 4000 Hz, what frequency does the stationary observer receive as the plane approaches? (b) As the plane flies away? Si mire barn Circha​

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.

k2s for potassium sulphide