When an oblique ray of light enters one medium from another (optically different or dispersive medium) then it changes its path. Such a phenomenon is called refraction.
Laws of refraction there are two laws of refractions
1μ2 = sin I/sin r
μ = sin I/sin r = c/v or v1/v2) = 1/sin C
Where C is critical angle.
μ = sin (A + Dm/2) in prism, where
μ = sin A/2
δ = (μ - 1) α
If angle of prism a is small and δ is angle of minimum deviation
μ = A + B/λ2 + C/λ4 is Cauchy’s principle
1μ3 = 1 μ2 x 2μ3 2μ1 = 1/1μ2
Incident ray normal and refracted rays are coplanar
Fermat’s principle:- when a ray of light passes from one point to another by any number of reflections and refractions, the path taken by light ray is the one for which the corresponding time taken is the least (or has shortest optical path).
Optical path length:- is μl if l is the distance travelled in a medium of refractive indexμ.
Refraction through a curved surface
μ2/v – μ1/u = μ2 – μ1/R
In all curved surfaces this formula can be applied with appropriate sign convention and remembering thatμ1 is the refractive index of the medium in which object lies.
Dispersive power ω = δv – δr/δ = μv – μr/μ = 1
Where δv and δr are minimum deviations for violet and red colours, δ is mean deviation (for yellow colour) μv and μr are refractive indexes for violet and red colours and μ is refractive index for yellow or mean colour.
δ = δv + δr/2 (if δ is not given)
Similarly μ = μv + μr/2 (if μ is not given)
ωδ = δv – δr is called angular dispersion
Angular dispersion ∝ 1/λ3
In a prism I + e = A + D
Note that D is minimum for a particular I, called angle of minimum deviation and is denoted by Dm
At minimum deviation I = e, r1 = r2 and ray through prism, is parallel to base of the prism.
ExpertsMind.com - Physics Help, Optical Physics Assignments, Refraction Assignment Help, Refraction Homework Help, Refraction Assignment Tutors, Refraction Solutions, Refraction Answers, Optical Physics Assignment Tutors