Optics Question 939
Question: Image formed by a concave mirror of focal length 6 cm, is 3 times of the object, then the distance of object from mirror is
[RPMT 2000]
Options:
A) - 4 cm
B) 8 cm
C) 6 cm
D) 12 cm
Show Answer
Answer:
Correct Answer: A
Solution:
m = ± 3 and f = ? 6 cm Now $ m=\frac{f}{f-u}\Rightarrow \pm 3=\frac{-6}{-6-u} $
For real image $ -3=\frac{-6}{-6-u} $
Therefore $ u=-8cm $
For virtual image $ 3=\frac{-6}{-6-u} $
Therefore $ u=-4cm $
