Magnification – Part 3

Table of Contents

• Magnification
• Derivation of the Magnification Formula
• Summary
• What’s Next?

In the previous segment, we looked at some Examples of magnification. In this segment, let us understand the derivation of the magnification formula.

What is Magnification?

• If the size of the object and the image is given by ℎ and ℎ respectively, then? = ℎ? .

? ?

• If ℎ? > ℎ?, then ? > 1. So the image is enlarged.

ℎ?

• If ℎ? < ℎ?, then ? < 1. So the image is diminished.
• If ℎ? = ℎ?, then ? = 1. So the image is of the same size as that of the object.
• If the distance of the object from the mirror is u and the distance of its image from the

mirror is v, then m = ℎ? = −?.

ℎ? ?

How is the magnification formula derived?

Consider a concave mirror as shown below.

Figure 1

Let the size of the object be ℎ? and the size of the image be ℎ?.OP is the incident ray of light and PI is the reflected ray of light. Let the distance of the object and that of its image from the

mirror be u and v respectively.