Birefringence is the phenomenon in which light passing through a material with a different refractive index (the ratio of the speed of light in a vacuum to the...
Birefringence is the phenomenon in which light passing through a material with a different refractive index (the ratio of the speed of light in a vacuum to the speed of light in the material) exhibits different properties depending on the direction of propagation. This means that light traveling through a material with a higher refractive index will bend towards the normal, while light traveling through a material with a lower refractive index will bend away from the normal.
An example of birefringence is the different colors of light observed in a rainbow. When sunlight passes through water droplets suspended in the air, the different wavelengths of light (blue, orange, red) are refracted at different angles, causing them to spread out into a spectrum.
Another example of birefringence is the way that light is refracted when it passes from water to air. The refractive index of water is higher than that of air, so light traveling through water is refracted away from the normal. This causes the light to bend towards the normal when it enters the air