Question

. A 10 cm tall object is placed perpendicular to the principal axis of a convex lens of focal length 30 cm. The distance of the object from the lens is 20 cm. Find the:

Answer 1

Missing point in question :-  (i) position (ii) nature (iii) size of the image formed.

Answer -

Given that,

Height of object h = 10 cm

Focal length f = 30 cm

The distance of the object u = -20 cm

Using lens's formula

1/f = 1/v – 1/u

1/30 = 1/v – 1/-20

1/30 = 1/v + 1/20

V = -60 cm

M = v/u = -60/-20 = 3

M = 3

 

Size of image = h’/h  

h’ =  Size of image x h

h’ = 3 x 10 = 30 cm

Answer 2

Explanation:

ho=10cm

f=30cm

u=-20cm

using lens formula

1/f=1/v-1/u

1/30=1/v-1/-20

v=-60

magnification

m=v/u

-60/-20

m=3

size of image =h'/h

h'=size of image×h

h'=3×10

=30cm