How is the power of a lens related to its focal length? How does sign ($+$or$-$) of power of a lens determine its divergent or convergent action? How does the power of lens change its focal length is doubled? 

Where should an object be placed in front of a lens to obtain an upright enlarged image?

Where should an object be placed in front of a lens to obtain real, inverted, same sized image?

Where should an object be placed in front of a lens to obtain real, inverted, highly diminished image?

Where should an object be placed in front of a concave lens to obtain a virtual, erect, diminished image?

Where should an object be placed in front of a lens to obtain a real, inverted, diminished image? Draw a ray diagram for the same.

Define and explain
Converging lens made up of number prisms and glass slab.