A) 16 cm above water level
B) 9 cm above water level
C) 24 cm below water level
D) 9 cm below water level
Correct Answer: B
Solution :
[b] Sun is at infinity i.e. \[u=\infty \] so from mirror formula we Have \[\frac{1}{f}=\frac{1}{-32}+\frac{1}{(-\infty )}\Rightarrow f=-32cm.\] When water is filled in the tank up to a height of 20 cm, the image formed by the mirror will act as virtual object for water surface. Which will form its image at I such that \[\frac{Actual\,height}{Apperant\,height}=\frac{{{\mu }_{w}}}{{{\mu }_{a}}},\]i.e., \[\frac{BO}{BI}=\frac{4/3}{1}\] \[\Rightarrow BI=BO\times \frac{3}{4}=12\times \frac{3}{4}=9cm.\]You need to login to perform this action.
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