Optics Question 954
Question: A plane mirror is made of glass slab $ ({\mu _{g}}=1.5)2.5cm $ thick and silvered on the back. A point object is placed 5 cm in front of the unsilvered face of the mirror. What will be the position of final image:
Options:
A) 12 cm from front face
B) 14.6 cm from front face
C) 5.67 cm from front face
D) 8.33 cm from front face
Show Answer
Answer:
Correct Answer: D
Solution:
[d] Let, $ I _{1},I _{2} $ and $ I _{3} $ be the images formed by:
(i) refraction from ABC
(ii) reflection from DEF and
(iii) again refraction from ABC
Then $ BI _{1}=(5)({\mu _{g}})=(5)(1.5)=7.5cm $
Now, $ EI _{1}=(7.5+2.5)=10cm $
Hence, $ EI _{2}=10cm $ behind the mirror
$ BI _{2}=(10+2.5)=12.5cm $
$ \therefore $ $ BI _{3}=\frac{12.5}{{\mu _{g}}}=\frac{12.5}{1.5}=8.33cm $
The ray diagram is as follow:
