Question

2. Rakesh placed an object at a distance of 15 cm form a convex mirror whose focal length 7.5 cm Find image distance.​

Answer 1

Answer:

The lens formula is given as,

The lens formula is given as,v1−u1=f1

The lens formula is given as,v1−u1=f1v1−(−15)1=101

The lens formula is given as,v1−u1=f1v1−(−15)1=101v=30cm

The lens formula is given as,v1−u1=f1v1−(−15)1=101v=30cmThe coincidence is possible when the image is formed at the centre of curvature of the mirror. Only then the rays refracting through the lens will fall normally on the convex mirror and retrace their path to forma the image at the place of object.

The lens formula is given as,v1−u1=f1v1−(−15)1=101v=30cmThe coincidence is possible when the image is formed at the centre of curvature of the mirror. Only then the rays refracting through the lens will fall normally on the convex mirror and retrace their path to forma the image at the place of object.The distance from the lens to the mirror is given as,

The lens formula is given as,v1−u1=f1v1−(−15)1=101v=30cmThe coincidence is possible when the image is formed at the centre of curvature of the mirror. Only then the rays refracting through the lens will fall normally on the convex mirror and retrace their path to forma the image at the place of object.The distance from the lens to the mirror is given as,d=30−12

The lens formula is given as,v1−u1=f1v1−(−15)1=101v=30cmThe coincidence is possible when the image is formed at the centre of curvature of the mirror. Only then the rays refracting through the lens will fall normally on the convex mirror and retrace their path to forma the image at the place of object.The distance from the lens to the mirror is given as,d=30−12d=18cm

Answer 2

Given :

In convex mirror,

Object distance : 15 cm.

Focal length : 7.5 cm.

To find :

The image distance of the mirror.

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,

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

$\dashrightarrow\sf \dfrac{1}{v} + \dfrac{1}{ - 15} = \dfrac{1}{7.5}$

$\dashrightarrow\sf \dfrac{1}{v} - \dfrac{1}{15} = \dfrac{1}{7.5}$

$\dashrightarrow\sf \dfrac{1}{v}= \dfrac{1}{7.5} + \dfrac{1}{15}$

$\dashrightarrow\sf \dfrac{1}{v}= \dfrac{2 + 1}{15}$

$\dashrightarrow\sf \dfrac{1}{v}= \dfrac{3}{15}$

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

$\dashrightarrow\sf v = 5 \: cm$

Thus, the image distance is 5cm.