Question

An object of height 4.0 cm is placed at the distance 24cm in front of a convex lens of focal length 8cm. (a) find the position and size of the image. (b) State the characteristics of the image.​

Answer 1

Given :

0 = 4.0 cm (positive),

u = 24 cm (negative),

f = 8 cm (positive)

(a) from relation 1/v - 1/u = 1/f , 1/v = 1/u + 1/f

or 1/v = 1/-24 + 1/8 = 1/12

v = 12 cm

the image is at distance 12cm behind the lens.

from relation I/O = v/u, I/0.4 = 12/-24

or I = -12/24 × 4 = -2 cm

thus the image is inverted of size 2 cm .

(b) Characteristics bof the image : the image is real, inverted and diminished (size 2.0cm).

thanks ❤️

Answer 2

Given

Ho= 4cm

u = 24Cm

f = 8cm

we know that

1/f = 1/v - 1/u

1/v = 1/f + 1/u

1/v = (u+f )/uf

v = uf/(u+f)

v= 24*8/32= 6cm

we know that

v/u = Hi/Ho

Hi = 6*4/24 = 1cm

Characteristics

real

inverted

diminished