Question

an object is placed at 30 cm from a concave mirror of focal length 10 centimetre calculate magnification of the image formed​

Answer 1

Answer:

Magnification=v/u

u=-30

v=-x

f=-10

According to Mirror formula

1/f=1/u+1/v

Or, 1/x+1/30=1/10

Or, 1/x=3-1/30

Or, 1/x=1/15

Or, x=15 (The value of v )

Magnification:v/u=15/-30

=-1/2

Answer 2

Answer:

Magnification of the image formed is -0.5

Explanation:

Things to Know:

Concave mirror : A concave mirror is a type of spherical mirror in which, the reflecting surface is the inner curved surface of the sphere

Mirror formula,

$\sf{\dfrac{1}{f} = \dfrac{1}{v}+ \dfrac{1}{u} }$

Linear magnification for mirror,

$\sf{m = - \dfrac{v}{u}}$

Where,

u = object distance

v = image distance

f = focal length

m = linear magnification

Given:

A concave mirror with,

u = -30 cm

f = - 10 cm

To find:

m = ?

Solution:

Using the mirror formula,

   $\sf{\dfrac{1}{f} = \dfrac{1}{v}+ \dfrac{1}{u} }$

$\implies \sf{ - \dfrac{1}{10} = \dfrac{1}{v} + \left( -\dfrac{1}{30} \right) }$

$\implies \sf{\dfrac{1}{30} - \dfrac{1}{10} = \dfrac{1}{v} }$

$\implies \sf{\dfrac{1}{v} = \dfrac{1-3}{30} }$

$\implies \sf{\dfrac{1}{v} = \dfrac{-2}{30} }$

$\implies \sf{\dfrac{1}{v} = - \dfrac{1}{15} }$

$\implies \sf{ v = -15 }$

Now,

Using linear magnification,

   $\sf{m = - \dfrac{v}{u}}$

$\implies \sf{m = \dfrac{\not-(-15)}{\not-30}}$

$\implies \sf{m = \dfrac{-15}{30}}$

$\implies \sf{m = \dfrac{-1}{2}}$

$\implies \sf{m = - 0.5}$

Hence,

Magnification = - 0.5