Refraction of Waves...
The paths of P and S waves curve because of the increase of pressure and temperature with depth in the Earth.
| The figure shows an imaginary planet made of a single
material. The density of the material, r, increases with depth in the planet. The elasticity, E, also increases with depth. The speed v of P and S waves depends on both these properties: E increases more rapidly than r with depth, so the waves gradually speed up the deeper they go in the planet. As the speed gradually changes the waves gradually change direction and follow arcs inside the planet. The changing of speed of a wave as it travels through a material and its consequent change in direction is called refraction.
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The wave which travels in
the same direction as the change in density and viscosity occurs is speeded up as it goes
deeper in the planet, but does not undergo any change in direction. Why?
