Class 12 NEET Physics Optics Questions Part 2

Using lens formula for first refraction from convex lens

1

v1

−

1

u

=

1

f

v1=?,u=−60 cm,f=30 cm
⇒

1

v1

+

1

60

=

1

30

⇒v1=60 cm
I1 here is first image by lens
The plane mirror will produce an image at distance 20 cm to left of it.
For second refraction from convex lens,
u = –20 cm, v = ? , f = 30 cm

1

v

−

1

u

=

1

f

⇒

1

v

+

1

20

=

1

30

⇒

1

v

=

1

30

−

1

20

⇒v=−60cm
Thus the final image is virtual and at a distance, 60 – 40 = 20 cm from plane mirro