Question

Collect the information about the lenses available in an optical shop find out how the focal legnth of a lens may be determined by the given power of lens

Answer 1

Lens is a position, of a transparent refracting medium which is bounding by the coaxial spherical surfaces. There are two types of lenses,
i) Convergent lenses : There are thick at centre and thin near edges. They bend the rays towards centre of the lens. They are divided into three categories.


ii) Divergent lens : These are thin at the centre and thick near edges. They bend the rays towards the edges of the lens. They are also further divided into 3 categories. The power of a lens is defined as the reciprocal of focal length of the lens. It is measured in diapters.



Answer 2

hi..! 
 there are so many lenses available .. some r 
concave lense,convex lens , plano lense, cylinder lens and achromatic lens 
 these some lense which r avaliable in d optical shop