Question

The power of a combination of two lenses in contact is + 1.0 D. If the focal length of one of the lenses of the combination is + 20.0 cm, the focal length of the other lens would be​

Answer 1

Step-by-step explanation:

Focal length of each lens is given as f

1

=0.20 m and f

2

=0.30 m.

Focal length of the combination

F

1

=

f

1

1

+

f

2

1

∴

F

1

=

0.20

1

+

0.30

1

⟹ F=0.12 m

Power of lens P=

f

1

Power of first lens P

1

=

0.20

1

=5D

Power of second lens P

2

=

0.30

1

=3.33D

Power of combination of lens P

c

=

F

1

⟹ P

c

=

0.12

1

=8.33D