Question

an object is placed in front of convex mirror at foal length 12cm. find out the object distance if the image distance is 8cm

Answer 1

Given :

In convex mirror,

Focal length = 12 cm

Image distance = 8 cm

To find :

The object 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,

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

$\dashrightarrow\sf \dfrac{1}{8} + \dfrac{1}{u} = \dfrac{1}{12}$

$\dashrightarrow\sf\dfrac{1}{u} = \dfrac{1}{12} - \dfrac{1}{8}$

$\dashrightarrow\sf\dfrac{1}{u} = \dfrac{2 - 3}{24}$

$\dashrightarrow\sf\dfrac{1}{u} = \dfrac{ - 1}{24}$

$\dashrightarrow \underline{\boxed{\sf u = - 24 \: cm}}$

Thus, the object distance is -24 cm