Question

An object is placed on the principal axis of convex lens of focal length $10 cm$ as shown A plane mirror is placed on the other side of lens at a distance of $20 cm$ The image produced by the plane mirror is $5 cm$ inside the mirror The distance of the object from the lens is ___$cm$

Answer 1

The correct answer is 30.

f=10cm
v1​−u1​=f1​
151​−−u1​=101​
⇒u1​=101​−151​
On solving we get value of u as 30cm.