Question

convex. lens of focal length 6 cm is held 4 cm from a newspaper which has print 0.5 cm high determine size of img produced

Answer 1

f = 6 cm
u = -4 cm
h = 0.5 cm
v = ?
h' = ?

By lens formula,
1/f = 1/v - 1/u
1/f + 1/u = 1/v
1/6+1/-4 = 1/v
1/v = 1/6-1/4
= 4 - 6/6*4
= -2/24
V =24/-2 = -12 cm
m = h'/h = v/u
H'/0.5 = -12/-4
= 3
H' = 3*0.5
=1.5 cm

Answer 2

Answer:

Explanation:

f = 6 cm

u = -4 cm

h = 0.5 cm

v = ?

h' = ?

By lens formula,

1/f = 1/v - 1/u

1/f + 1/u = 1/v

1/6+1/-4 = 1/v

1/v = 1/6-1/4

= 4 - 6/6*4

= -2/24

V =24/-2 = -12 cm

m = h'/h = v/u

H'/0.5 = -12/-4

= 3

H' = 3*0.5

=1.5 cm