When the convergent nature of a convex lens will be less as compared with air

When does a convex lens behave as a concave lens ?

When does a convex lens behave as a concave lens ?

A convergent beam is incident on a convex lens. What will be the nature of the image formed ?

Assertion :Property of lens, whether the ray is converging or diverging is independent of the surrounding medium. Reason : The converging property of a convex lens does not be same in all media.

A beam of light converges at a point P. Now a convex lens is placed in the part of the converngent beam at 15 cm from P. At what point does a beam converge if the convex lens has a focad length 10 cm ?

A beam of light converges at a point P. Now a convex lens is placed in the part of the converngent beam at 15 cm from P. At what point does a beam converge if the convex lens has a focad length 10 cm ?

The radius of curvature of the convex surface of a planoconvex lens is 12 cm and its refractive index 1.5. If the plane face of the lens is silvered, then the distance from the lens at which parallel rays incident on its convex surface converge is