JEE MAIN - Physics (2020 - 6th September Morning Slot - No. 6)
A point like object is placed at a distance of 1 m in front of a convex lens of focal length 0.5 m. A
plane mirror is placed at a distance of 2 m behind the lens. The position and nature of the final
image formed by the system is :
2.6 m from the mirror, real
1 m from the mirror, real
2.6 m from the mirror, virtual
1 m from the mirror, virtual
Explanation
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Object is at 2f. So image will also be at 2f. (I1).
Image(I2) of I1 will be 1 m behind mirror.
Now I2 will be object for lens.
$$ \therefore $$ u = -3 m
f = + 0.5 m
$${1 \over v} = {1 \over f} + {1 \over u}$$
= $${1 \over {0.5}} + {1 \over { - 3}}$$
$$ \Rightarrow $$ v = $${3 \over 5}$$ = 0.6 m
So total distance from mirror = 2 + 0.6 = 2.6 m and real image.
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