#### Refraction

incoming
ray
medium that
has the lower
velocity
medium that
has the higher
velocity
refracted
ray

Figure 1: Refraction

incoming
ray
medium that
has the lower
velocity
medium that
has the higher
velocity
refracted
ray

Figure 1: Refraction

Refraction is the change in direction of a wave due to a change in its speed. Radio waves passing through the atmosphere are affected by certain factors, such as temperature, pressure, humidity, and density. These factors can cause the radio waves to be refracted as they move from one medium into another in which the velocity of propagation is different. Refraction occurs when a wave traveling through two different mediums passes through the boundary of the mediums and bends toward or away from the normal. This bending is always toward the medium that has the lower velocity of propagation.

Snell's Law of Refraction describes the relationship between the incident and the refracted rays when light rays encounter the boundary between two different transparent materials and is shown in this formula:

 n = sin α (1) sin β

Figure 2: a laser pointer and an acrylic block.

Figure 2: a laser pointer and an acrylic block.

The refractive index n is independent of the varying angles of incidence α. It is even of the relationship of the different velocities of propagation in the different media.