Optics Question 692
Question: Two lenses of power + 12 and -2 diopters are placed in contact. The combined focal length of the combination will be
[Pb. PET 2004]
Options:
A) 8.33 cm
B) 1.66 cm
C) 12.5 cm
D) 10 cm
Show Answer
Answer:
Correct Answer: D
Solution:
$ P=P _{1}+P _{2} $
$ =+12-2=10D $ Now $ F=\frac{1}{P}=\frac{1}{10}m $
$ =\frac{1}{4}+\frac{1}{-5}=\frac{1}{20} $ .
