Ray Optics and Optical Instruments Class 12 Notes Physics Chapter 9


1. Reflection of light : If is the turning back of light in the same medium.

2. Laws of reflection :
(i) Incident ray, reflected ray and normal all three lie in the same plane.
(ii) Angle of incidence Li = angle of reflection Lr

3. Spherical mirror: For radius of curvature R, the focal length of spherical mirror will be f = R/2 . For convex mirror it is + f and for concave mirror it is -f.

11. Dispersion produced by prism : It is splitting of white light into its seven constituents colours.

12. The refractive index of material of a prism depends on wavelength of light. It approximately is given by Cauchy’s equation as:

14. Combination of prisms mean deviation or w

(i) Dispersion without deviation :
(ii) Deviation with dispersion :
For two small angled prisms, we have

21. Combined focal length

23. Compound microscope

24. Astronomical telescope

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