Question

if two lenses having focal length 25 cm and 50 cm are kept in contact. Find the focal length and power of equivalent lenses​

Answer 1

Answer:

First converting fin metres so lens 1 has

f=0.2m and lens 2 has f=0.25m

Power of lens1=

0.2

1

=5D

Power of lens2=

0.25

1

=4D

Effective power =P

1

+P

2

=5D+4D=9D