Question

An object is situatied 25cm in front of a plane mirror.
Determine the distance of the image from the object.
What is the size of the image relative to the object?

Answer 1

Answer:

Explanation:distance is 50 because the distance of object from the is equal to the image in the mirror and its size will also be same

Answer 2

Answer:  Image is formed at a distance of 50 cm from the object and its size is same as that of the object.

Explanation:

Mirror formula :  $\frac{1}{v} + \frac{1}{u} = \frac{1}{f}$

v  ⇒ Image distance

u ⇒ Object distance

f  ⇒ Focal length of mirror

Radius of curvature of plane mirror is infinity. Hence, its focal length is also infinity.

f → infinity

⇒ 1/f → 0

$\frac{1}{v} + \frac{1}{u} = \frac{1}{f}$

For plane mirror :

$\frac{1}{v} + \frac{1}{u} = 0$

$\frac{1}{v} = - \frac{1}{u}$

$v = -u$

Given,

Object is placed 25 cm in front of mirror

⇒ u = -25 cm

∴ v = -(-25cm)

v = 25 cm

Image is formed 25 cm behind the mirror.

Distance between image and object = 25 + 25 = 50 cm

v = -u

$\frac{-v}{u} = 1$

$m = \frac{-v}{u} = 1$  

Magnification is 1.

∴ The size of object and image is same.

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