A biconvex lens of focal length is in front of a plane mirror. The distance between the lens and the mirror is . A small object is kept at a distance of from the lens. The final image is
virtual and at a distance of from the mirror
real and at a distance of from the mirror
virtual and at a distance of from the mirror
real and at a distance of from the mirror
Focal length of the biconvex lens is . A small object is placed at a distance of from the lens i.e. at a distance of . Therefore the image should form at from the lens at
But since the ray strike the plane mirror before reaching , the image acts as the virtual object for reflection on plane mirror kept at a distance of from it. It should produce an image but as the ray encounters the lens, it gets refracted and the final image is formed at . For the last refraction from the biconvex lens,
Applying lens formula
Therefore a real image is formed at a distance of from the plane mirror.
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