Refraction
The bending of a ray of light when it goes from one to another is called refraction.
When Light travels from ...
When light travels from a rarer to a denser medium it is refracted the normal.
When light travels from a denser to a rarer medium it is refracted from the normal.
The Laws of Refraction of Light
1st Law: The incident ray, the normal ray at the point of incidence and the refracted ray all lie in the same .
2nd Law: The ratio of the of the angle of incidence to the of the angle of refraction is a constant.
i.e. sin i /sin r = n, where n is a constant.
Refractive Index of a Medium
The refractive index of a medium is the ratio of the sine of the angle of incidence to the sine of the angle of refraction when light travels from a into that medium.
The Refractive Index Between Two Media
The refractive index between two media is the of the sine of the angle of incidence to the sine of the angle of refraction when light travels from one of those into the other.
Critical Angle
When light travels from a denser to a rarer medium
the angle of incidence whose corresponding angle of refraction is ° is called the critical angle (C) for those two media.
Total Internal Reflection
When light going from a denser to a rarer medium strikes the second medium with an angle of incidence greater than the angle, it does not enter the second medium. It is back into the denser medium. This is called total internal reflection.
Optical Fibre
A very thin transparent rod (usually of glass) through which light can travel by total reflection is called an optical fibre.
For a Convex Lens
If the object is outside the the image is real and located at the opposite side of the lens to the object. The image is .
If the object is inside the focus the image is virtual and is located at the same side of the lens as the object. The image is upright ().