The Refraction of Light Waves:
The bending of light is known as Refraction. When light travels from a optical less dense media such as air into a dense media such as glass,light will refract/bend towards the normal line and the speed and wavelength of the light will decrease. When light travels from a optical dense media into a less optically dense media, light will refract/bend away from the normal as it exits the dense medium.The speed and wavelength of the light will increase. When closely observed, the light will also change the direction it travels as it passes through the two media (Air to Glass). The transmitted wave/light will experience refraction at the boundary between media. As we observe the diagram on the right, the individual wavefronts will bend as it cross the boundary. Once the wavefront cross the boundary, it travels in a straight line, hence why refraction is known as a boundary behaviour. The diagram shows a ray drawn perpendicular to the wavefronts which represents the direction which light travels. We can see that the rays travel in a straight line inside of the two media, and bends at the boundary.
To find out change of speed of light as it travels from the air into glass, we can use the Refractive Index formulae; which is a measure of how much the light slows down as it enters the dense medium (glass). The formulae is written as:
Refractive Index: Speed in Air / Speed in a material
Light travels at 3 x 10^8 ms^-1 in air while light travels 2 x 10^8