Page 26 - cbse-class-10-light-reflection-and-refraction

Magnification is defined as the ratio of the image's height to the object's height.
The letter m is commonly used to represent it.

If h is the object's height and h' is the image's height, then the magnification m
produced by a spherical mirror can be written as

h 
m 
h

The magnification ‘m’ is also related to object distance (u) and image distance (v).
It can be expressed as:

h  v
m   
h u

The negative sign in the value of the magnification indicates that the image is real.
A positive sign in the value of the magnification indicates that the image is virtual.

Refraction The deviation in the path of light when it passes from one medium to
another medium of different density is called refraction.

The twinkling of stars is due to atmospheric refraction of starlight. Since light
bends towards the normal the apparent position of the star is slightly different from
its actual position as it passes through the atmosphere. Hence the star appears
slightly higher than its actual position. Due to changing condition of earth's
atmosphere the apparent position of the star changes slightly and the intensity of
light reaching the eye also fluctuates. This gives rise to the twinkling effect of the
star.

Incident Ray (IO)

The ray of light striking the surface of separation of the media through which it is
traveling is known as the incident ray.

Point of Incidence (O)

The point at which the incident ray strikes the surface of separation of the two
media is called the point of incidence.

Normal (N)

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