REFLECTION OF LIGHT

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REFLECTION OF LIGHT

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Definition: When a light ray strikes the boundary between two media such as air and glass, a part of that light is reflected.

By reflection we mean the bouncing back of the radiant energy at the boundary between the two media and this is the reason for the visibility of non–luminous bodies.

LAWS OF REFLECTION:

(1) The incident ray, the reflected ray and the normal to the surface lie in the one plane.

(2) The angle of incidence is equal to angle of reflection.

REFLECTION OF LIGHT BY A PLANE SURFACE:

Characteristics of reflection by a plane surface:

(1) The image formed is at the same distance, behind the reflecting surface as the object is in front.

(2) The line joining the object point with its image is normal to the reflecting surface.

(3) The size of the image is the same as that of the object.

(4) The image is laterally inverted.

(5) The image is virtual which means no light actually passes through it.

(6) For a fixed incident ray, if mirror be rotated through an angle q, the reflected ray turns through an angle 2q from its initial path.

(7) To view full image, a person needs a plane mirror of length equals to half the height of person.

(8) If two mirrors are kept inclined to each other at an angle ‘q’ with their reflecting surfaces facing each other, multiple reflection take place and images more than one are formed.

Number of images formed:

I.Total no. of images seen =\frac{{360}}{\theta }, if\frac{{360}}{\theta }is odd.

II.Total no. of images seen = \frac{{360}}{\theta } - 1, if  \frac{{360}}{\theta } is even.