Question

how does the newtons ring work?

Answer 1

Newton rings :-

Newton ring formes between two surfaces due to interferance of light between spherical surfaces and adjacent flat surface touching each other.

Concept Behind:-

Interferance causes redistribution of energy by superposition of light waves. So when two or more superimpose on each other final intensity of light gets modified and forms maximum intensity in one place and minimum intensity on other place.

So when a planoconvex lens in placed over flat glass surface then we see that circular air film of gradually increasing thickness from center of lens to rim of lens gets formed.

So when we incident parralel light rays from lens on glass plate mounted at 45 degree which falls parralel light rays on the plano convex lens and Interference takes place between light reflected from flat glass surface and refracted light whch makes circular rings of adjacent maximum and minimum intensity between them.

and wavelength of light can be calculated from formula

Dn is diameter of nth maximum ring

and R is the Radius of curvature of lens