Question

An object is placed at a distance of 10cm from convex mirror of focal length 20cm.Find the nature and position of image?​

Answer 1

Explanation:

Given that

u= -10 cm

f= 15 cm

We need to find v

We know the formula

1/f = 1/v + 1/u

Therefore, 1/v= 1/f – 1/u

Substituting the known values in the above equation we get,

1/v= 1/15 + 1/10

1/v = (2+3)/30 (lcm)

Hencev=5/30 = 6 cm

v= 6cm

Nature of the image: The image is formed behind the mirror and it is virtual and erect.

Answer 2

Given :

In convex mirror,

Object distance = 10 cm

Focal length = 20 cm

To find :

The nature and position of image.

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,

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

$\dashrightarrow\sf \dfrac{1}{v} + \dfrac{1}{ - 10} = \dfrac{1}{20}$

$\dashrightarrow\sf \dfrac{1}{v} - \dfrac{1}{ 10} = \dfrac{1}{20}$

$\dashrightarrow\sf \dfrac{1}{v} = \dfrac{1}{20} + \dfrac{1}{ 10}$

$\dashrightarrow\sf \dfrac{1}{v} = \dfrac{1 + 2}{20}$

$\dashrightarrow\sf \dfrac{1}{v} = \dfrac{3}{20}$

$\dashrightarrow\sf v = \dfrac{20}{3}$

$\dashrightarrow\sf v = 6.66 \: cm$

Thus, the position of image is 6.66 cm.

Nature of image :

• The image is real and inverted.