Refraction at Plane Surfaces Refraction refers to the change in direction of a beam of light as it transitions from one medium to another. This can occur whe...
Refraction refers to the change in direction of a beam of light as it transitions from one medium to another. This can occur when the speed of light changes depending on the properties of the two mediums, or when the angle of incidence exceeds the critical angle.
Key points:
Light traveling from a denser medium to a less dense medium:
The light bends away from the normal (the angle of incidence is greater than the critical angle).
This is why we see the inside of a glass object from outside.
Light traveling from a less dense medium to a denser medium:
The light bends towards the normal (the angle of incidence is less than the critical angle).
This is why we see the outside of a glass object from outside.
Critical angle:
This is the angle of incidence at which the light ray strikes the surface of the medium with the greatest angle of incidence and is totally reflected back into the medium.
It depends on the properties of the two media and can be calculated using the formula: θ_c = sin^{-1} (n_s) where:
θ_c is the critical angle
n_s is the refractive index of the denser medium
n_l is the refractive index of the less dense medium
Factors affecting refraction:
The angle of incidence
The refractive indices of the two mediums
The speed of light in each medium
Examples:
When you look through a window at a book, the light bends away from the normal. This is because the refractive index of glass is greater than that of air, so light travels slower in glass than in air.
When a light ray strikes the surface of a glass object, it can be totally reflected back into the object due to the critical angle being greater than the angle of incidence.
Light traveling through a lens is refracted as it enters the lens. This can be used to focus light onto an object at a specific distance