A student is finding focal length of convex mirror by using a convex lens. He fixes the positions of object needle at 
, convex lens at 
and convex mirror on optical bench at 
mark. He removes the parallax between object needle and its image. If convex lens has focal length 
then the focal length of convex mirror used by him is :
A
B
C
D
Text Solution
Verified by ExpertsThe correct answer is:
A
For the lens 
from lens formula
Now from figure for convex mirror
focal length of the mirror 
.
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