Question

we are given a convex lens of focal length 20 cm. Draw any ray daigrams yo show the nature,size and position of the image formed when the object is kept at a distance of 55cm​

Answer 1

$\large\underline{\underline{\sf Given:}}$

• Focal Lenght of Convex lens (f) = 20

• Object placed at (u) = -55cm

$\large\underline{\underline{\sf To\:Find:}}$

• Position of image (v) = ?

• Nature of image & size.

$\large\underline{\underline{\sf Solution:}}$

According to Lens formula

$\large{\boxed{\sf \frac{1}{f}=\frac{1}{v}-\frac{1}{u} }}$

$\large\implies{\sf \frac{1}{20}=\frac{1}{v}-\frac{1}{-55}}$

$\large\implies{\sf \frac{1}{20}=\frac{1}{v}+\frac{1}{55} }$

$\large\implies{\sf \frac{1}{v}=\frac{1}{20}-\frac{1}{55} }$

$\large\implies{\sf \frac{1}{v}=\frac{-54+20}{20×-55}}$

$\large\implies{\sf v=\frac{-1100}{-35}}$

$\large\implies{\sf v=31.4cm}$

Nature of Image

• Image formed between F and 2F

• Image is real , inverted , small in size.

$\Large\underline{\underline{\sf Answer:}}$

•°• Image formed at 31.4cm.