what is an equiconvex lense?

plz explain what is convex and concave lens plz.. i dont have the basic concepts of them.

 

Equi-convex Lenses are a type of convex lenses in which the two opposite curved (spherical) surfaces have the same shape or slope. So, their radii of curvature (and focal lengths are equal).  Look ate the figure below for a better idea.

Convex Lens

A convex lens is made by joining two spherical surfaces in such a way that it is thicker at the centre. Its thickness gradually reduces as we move towards the edge.

A convex lens has the ability to converge incident light rays to a point. Thus, it is called a converging lens.

Concave Lens  

 A concave lens is made by joining two curved surfaces in such a way that it is thinner at the centre. Its thickness gradually increases as we move towards the edge.

A concave lens has the ability to diverge a beam of light rays incident on it. Thus, it is called a diverging lens.