Question

An object 25cm away from a converging lens of focal length 10cm . find the position and nature of the image gormed​

Answer 1

Given :

In converging lens (convex lens),

Object distance = -25 cm

Focal length = 10 cm

To find :

The position and nature of the image formed

Solution :

Using lens formula that is,

» The formula which gives the relationship between image distance, object distance and focal length of a lens is known as the lens formula.

The lens formula can be written as :

$\boxed{ \bf \dfrac{1}{v} - \dfrac{1}{u}= \dfrac{1}{f}}$

where,

v denotes image distance

u denotes object distance

f denotes focal length

by substituting all the given values in the formula,

$\dashrightarrow{ \sf \dfrac{1}{v} - \dfrac{1}{u}= \dfrac{1}{f}}$

$\dashrightarrow{ \sf \dfrac{1}{v} - \dfrac{1}{ - 25}= \dfrac{1}{10}}$

$\dashrightarrow{ \sf \dfrac{1}{v} + \dfrac{1}{ 25}= \dfrac{1}{10}}$

$\dashrightarrow\sf \dfrac{1}{v} = \dfrac{1}{10} - \dfrac{1}{25}$

$\dashrightarrow\sf \dfrac{1}{v} = \dfrac{5 - 2}{50}$

$\dashrightarrow\sf \dfrac{1}{v} = \dfrac{3}{50}$

$\dashrightarrow\sf v = \dfrac{50}{3}$

$\dashrightarrow\sf v = 16.67 \: cm$

Thus, the position of the image is 16.67 cm.

Nature of the image :

• The plus sign for image distance indicates that the image is formed on the right side of the lens.
• The image is real and inverted.