Question

An object is placed 10 cm from a concave mirror. The focal length is 5 cm, then the
image distance is​

Answer 1

Answer:

required formula is

1/v+1/u=1/f

u=10cm, f=5cm

v=?

Answer 2

Given :

In concave mirror,

Object distance : 10 cm

Focal length : 5 cm

To find :

The image distance

Solution :

Using mirror formula that is,

» A formula which gives the relationship between image distance, object distance and focal length of a sperical mirror is known as the mirror formula .i.e.,

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

where,

• v denotes Image distance
• u denotes object distance
• f denotes focal length

By substituting all the given values in the formula,

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

$\dashrightarrow\sf \dfrac{1}{v} + \dfrac{1}{ - 10} = \dfrac{1}{ - 5}$

$\dashrightarrow\sf \dfrac{1}{v} - \dfrac{1}{ 10} = \dfrac{1}{ - 5}$

$\dashrightarrow\sf \dfrac{1}{v} = \dfrac{1}{ - 5} + \dfrac{1}{ 10}$

$\dashrightarrow\sf \dfrac{1}{v} = \dfrac{ - 2 + 1}{ 10}$

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

$\dashrightarrow\sf v = - 10 \: cm$

Thus, the image distance is 10 cm.