RRB Technician 2014 Ques 30
Question: A simple microscope consists of a concave lens of power $ -10D $ and a convex lens of power $ +20D $ in contact. If the image formed at infinity, then calculate the magnifying power (D = 25 cm)
Options:
A) $ 2.5 $
B) $ 3.5 $
C) $ 2.0 $
D) $ 3.0 $
Show Answer
Answer:
Correct Answer: A
Solution:
- Power of combination, $ P=P _1+P _2 $ $ P=+20-10=+10D $ $ F=\frac{1}{P}=\frac{1}{10}m=\frac{100}{10}cm=10cm $ For final image at infinity $ M=\frac{D}{F}=\frac{25}{10}=2.5 $
BETA
