Question

A 5cm tall object is placed perpendicular to the principal axis of a convex lens of focal length 20cm . The distance of the object from the lens is 30cm.Find the position , nature and size of the image formed.

Answer this correctly plz​

Answer 1

Given:

• Height of object h = 5 cm
• Focal length f = 20 cm
• The distance of the object u = -30 cm

To Find:

The position, Nature, and size of image is formed.

Solution:

Using lens's formula

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

$\sf\Large\ \frac{1}{20}=\frac{1}{v}-\frac{1}{-30}$

$\sf\Large\ \frac{1}{v}=\frac{1}{60}$

$\dashrightarrow\: \underline{\boxed{\bf{\purple{v =60}}}}$

The image is formed at 60 cm on the other side from the lens.

The magnification is

$\sf\ m = \Large\ \frac{v}{u}$

$\sf\ m = \Large\ \frac{60}{-30}$

$\dashrightarrow\: \underline{\boxed{\bf{\purple{m= -2}}}}$

The image is real, inverted

Size of the image,

$\sf\ m = \Large\ \frac{h'}{h}$

$\sf\ -2 = \Large\ \frac{h'}{5}$

$\dashrightarrow\: \underline{\boxed{\bf{\purple{h' = -10 cm}}}}$

Hence, The size of the image is 10 cm and the image is real and inverted.

$\Large\underline\bold{Additional\: Information}$

• Image is a true reflection of body. It is formed by reflection of light rays by an object.
• The mean position is the center point where the bob completes half of its distance and there it possess only potential energy.
• Magnification is the ratio of the size of the image to that of the object.
• Real Images are formed on the left hand side of the lens/mirror.

$\rule{150}3$