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Some Topics of Physics

6. Spherical Mirrors : It is part of hollow glass sphere whose one surface is polished.
There are two types of spherical mirror.
(i) Concave Mirror : It is a spherical mirror whose outer surface is polished and inner or concave side is reflecting surface.
(ii) Convex Mirror : It is a spherical mirror whose inner is polished and outer side or convex side is the reflecting surface.
Principal Focus :
A point on the principal axis of a spherical mirror where the rays of light parallel to the principal axis meet or appear to meet after reflection from the mirror.
Focal Length :
The distance between the pole (P) and principal focus(F) of a spherical mirror is called the focal length of the mirror. It is denoted by f.

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Some topics of Physics

13. Refraction of Light :  The bending of ray of light when it passes from one medium to another is called refraction of light. Laws of Refraction : (i) The incident ray, the refracted ray and the normal at the point of incidence all lie in the same plane. (ii) When a ray of light undergoes refraction then the ratio of sine of angle of incidence to the sine of angle of refraction is constant. 14. The Refractive Index :  The refractive index of medium 2 with respect to medium is given by the ratio of the speed of light in medium 1 and the speed of light in medium 2. This is usually represented by the symbol n 21 . This can be expressed in an equation form as