Page 41 - cbse-class-10-light-reflection-and-refraction

Depending on the size and nature of the image, the magnification produced by a
lens can be equal to one, greater than one, or less than one.

Case I

When the image's height (h ) equals the object's height (h ).
I
o
h
m  I  1
h o

As a result, when the magnification is set to one, the size of the image is the same
as the size of the object.

Case II

When the image height (h ) is greater than the object’s height.
1

h
m  I  1
h o

The image is magnified

Case III

When the image’s height is lesser than the object’s height.

h
m  I  1
h
o

The image is diminished.

The height of the object is always positive for both types of lenses, whereas the
height of the image can be + or - depending on its nature. The height of an inverted
and real image is negative according to lens sign convention, and thus the
magnification of a lens is negative when it produces an inverted and real image.
The image's height is positive for an erect and virtual image. When an erect and
virtual image is formed, the magnification is positive.

Power of a Lens

Class X Science www.vedantu.com 41