List of top Physics Questions on spherical lenses asked in KEAM

If a thin lens of focal length 20 cm is in contact with another lens of power 4 D, then the effective power of the combination is

An effective power of a combination of 5 identical convex lens having focal length f= 20 cm is

An optician prescribes a lens of power +2.5 D. The focal length of the lens in water is (Indices: Lens = 1.5, Water = 1.33):

The magnification of an image by a convex lens is positive only when the object is placed

If the radius of curvature of the curved surface of a plano-convex lens is $50$ cm, its focal length is ($\mu = 1.5$)