A) convex mirror with focal length\[f=40\text{ }cm\]
B) convex mirror with focal length \[f=20\text{ }cm\]
C) concave mirror with focal length\[f=-40\text{ }cm\]
D) concave mirror with focal length\[f=-20\text{ }cm\]
Correct Answer: A
Solution :
\[M=\frac{I}{O}=\frac{v}{u}\] Given, \[O=8cm,\,I=4cm,v=60cm\] \[\therefore \] \[\frac{4}{8}=\frac{60}{u}\] \[\Rightarrow \] \[u-120cm\] \[\frac{1}{f}=\frac{1}{v}+\frac{1}{u}=\frac{1}{60}+\frac{1}{120}\] \[\Rightarrow \] \[f=40\,cm\] (convex)You need to login to perform this action.
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