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SAI INTERNATIONAL SCHOOL
Class 7
Lesson Notes
Subject-Physics
CH: Light and Associated Phenomena
Subtopic- Spherical Lens

REFRACTION:

It is a phenomenon in which light rays change its direction or bending of light occurs, when a ray
of light passes from one transparent medium to another.

RULES OF REFRACTION:
 When a ray of light goes from rarer medium to denser medium, it bends towards the
normal.

 When a ray of light goes from denser medium to rarer medium, it bends away from the
normal.

 When a ray of light travels along the normal, there is no deviation.

LENSES :

The curved refracting surface which is a part of a sphere is known as ‘spherical refracting
surface’.

SPHERICAL LENSES: A refracting material bounded by two surfaces with at least one curved
surface.

TYPES OF LENSES
There are two types of lenses:
(i) convex lens
(ii) Concave lens