Question

a) An object is placed on the principal axis of a convex lens at a distance of 24 cm
from it. If the focal length of the lens is 15 cm, what is the position of the image?
​

Answer 1

Answer:

Given u=−24cm,f=+8cm,v=?

Using the lens formula

f1=v1−u1⇒v1=f1+u1

v1=81+(−24)1=243−1=242=121

v=+12cm

Answer 2

Answer:

For the lens , f=15cm,

u=−30cm

From lens formula,

v

1

−

u

1

=

f

1

v

1

=

15

1

−

30

1

=

30

1

v = 30 cm

the image is formed at 30 cm of right side due to lens only.

Again, shift due to glass slab is,

= Δt=(1−

15

1

) 1 [ since, μ

g

= 1.5 and t = 1 cm ]

= 1−(

3

2

) = 0.33cm

The image wil be formula at 30+0.33=30.33cm from the lens on tight side.