Important Questions on Light - Reflection and Refraction
State whether u, v and f are positive or negative, when: the lens is convex and the image formed is real. 
State whether , and are positive or negative, when: the lens is convex and the image formed is virtual.
State whether , and are positive or negative, when: the lens is concave. What do you understand by the term linear magnification of the lens? State two formulae for the linear magnification. What do you understand by the term power of a lens? State and define the unit of the power of a lens. When is the power of the lens (a) positive, (b) negative? Draw a neat diagram to illustrate the use of convex lens as magnifying glass. 
