According to superposition principle, when two or more wave motions travelling through a medium superimpose one another, a new wave is formed in which resultant displacement at any instant is equal to the vector sum of the displacements due to individual vectors at that instant. This note provides us an information on the superposition principle.
The product of the distance travelled by the light in a medium and the refractive index of that medium is called the optical path. This note provides us an information on path difference, phase difference and Young's double slit experiment.
If the radius of curvature R of the lens is much greater than the distance r, and if the system is viewed from above, a pattern of bright and dark rings which are called Newton’s rings.