Optics Question 920
Question: A virtual image three times the size of the object is obtained with a concave mirror of radius of curvature $ 36cm. $ The distance of the object from the mirror is
[MP PET 1986]
Options:
A) $ 5cm $
B) $ 12cm $
C) $ 10cm $
D) $ 20cm $
Show Answer
Answer:
Correct Answer: B
Solution:
Image is virtual so m = + 3. and $ f=\frac{R}{2}=18\ cm $ .
So from $ m=\frac{f}{f-u}\Rightarrow 3=\frac{(-18)}{(-18)-u} $
$ \Rightarrow u=-\ 12\ cm. $
