Question

An object of height 2.5 cm is placed at a distance of 15 cm from the optical centre 'O' of a
of focal length 10 cm.
find the position and size of the image
formed
.​

Answer 1

Answer:

An object of height 2.5cm is placed at a distance of 15cm from the optical centre 'O' of a convex lens of focal length 10cm. Draw a ray diagram to find the position and the size of the image formed. Mark optical center 'O', principal focus F and height of the image in the diagram.

Medium

Video Explanation

Solution To Question ID 494659

Answer

Given : u=−15 cm F=+10 cm h

o

=2.5 cm

Using lens formula :

v

1

−

u

1

=

F

1

∴

v

1

−

(−15)

1

=

10

1

⟹F=+30 cm

Also m=

h

o

h

i

=

u

v

∴

2.5

h

i

=

−15

30

h

i

=−5 cm (- sign shows that image formed is inverted)

solution

Answer 2

Explanation:

Given : u=−15 cm

F=+10 cm

h°=2.5 cm

Using lens formula : 1/v-1/u=1/f

∴ 1/v-1/(−15)= 1/10

⟹F=+30 cm

Also m=hi/h°=v/u

∴ hi/2.5 = 30/(-15)

hi =−5 cm (- sign shows that image formed is inverted)