Q2 of 50 Page 43

What is called the magnification of an image? Derive the formula of magnification for spherical lens.

Magnification of an image is defined as the ratio of the height of image to the height of object.

Magnification (m) =



In the figure above by geometry we can easily see that ΔABO and ΔA’B’O’ are similar.


∴ …………… (1)


From definition of magnification.


Magnification (m) =


⇒ ……… (2)


From (1) and (2)


Magnification = which is the formula for magnification of lens.


More from this chapter

All 50 →
2

Draw a ray - diagram showing the position, nature and size of an image formed by convex lens when the object is placed between its optical centre and focus.

 2

Draw a ray - diagram showing the position, nature and size of an image formed by concave lens when the object is placed between at optical centre and infinite point.

 3

Explain the reflection by a plane mirror by drawing suitable figure.

 3

Give the Cartesian sign convention for the reflection by spherical mirror.