The distance between a seismological recording station and the earthquake source is determined from the the distance between a seismological recording station and the earthquake source is determined from the earthquake magnitude length of the seismic record arrival times of p and s waves intensity of the earthquake

Arrival times of P and S waves

Explanation:

Seismological recording station has a seismometer  that senses that motion in the ground, a clock that records time and a data recorded.

The distance between beginning of the first P wave and the first S wave will give you the time the waves are apart.This time value will be used to find the distance between the seismograph and the epicenter of earthquake and you mark it.This is corresponding distance in km to the time in seconds obtained  before.You then find the amplitude of the strongest wave and mark it on the right side of chart.Amplitude is the height on paper of the strongest wave.Using a ruler join the amplitude point and the point where you marked the distance to epicenter.This line will cross the magnitude chart at a point which represents the magnitude of the Earthquake.

6 cos 34, 6 sin 34 trig

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.