A point object O is placed on the principal axis of a convex lens of focal length f=20cm at a distance of 40 cm to the left of it.The diameter of the lens is 10 cm.An eye is placed 60cm to the right of lens and a distance h below the principal axis.The maximum value h to see image is_______________

1/40 +1/v =1/20,v=40cm to right of lens. Let image point be P. In order to see image, a ray emerging from P has to reach hmax below axis. the ray that reaches hmax would have to touch the top most point of the lens. This point, Q, is 5cm above the axis.let R be centre of lens and point 60 cm to right be S,let eye be E.

RQP and ESP are similat triangles

ES/QR=PS/PR, hmax/5=20/40, hmax=2.5cm