Differences between convex and concave lenses

Convex lenses                                        

• Convex lenses are also known as converging lenses or positive lenses.    

• Convex lenses are thicker in the centre than at the adge.  

• Convex lenses refract incident rays of light,which are parallel to the principal   axis. This point is called the real principal focus.

Concave lenses

• Concave lenses are also known as diverging lenses or negative lenses.
• Concave lenses are thinner in the centre than at edge.
• Concave lenses refract incident rays of light,which are parallel to the principal axis,so that they appear to diverge from a point located on the incident side of the principal axis.This point is called the virtual principal focus.