Question

a convex lens of focal length f1 is placed in contact with a concave lens of focal length f2 the combination acts as a diverging lens when​

Answer 1

Answer:

Convex lens has positive focal length whereas the concave lens has negative focal length.

∴ f

convex

=f

1

and f

concave

=−f

2

Focal length of the combination of lens

F

1

=

f

convex

1

+

f

concave

1

∴

F

1

=

f

1

1

+

−f

2

1

⟹F=

f

2

−f

1

f

1

f

2