You are given a convex lens of focal length $10\, cm$. Where would you place an object to get a real,inverted and highly enlarged image of the object? Draw a ray diagram.

Find the focal length of a convex lens,if its power is $+2.0 \ D$. (in $m$)

Define the term reflection.

$A$ student focussed the image of a candle flame on a white screen using a convex lens. He noted down the position of the candle,screen,and the lens as under:
Position of candle $= 12.0\, cm$
Position of convex lens $= 50.0\, cm$
Position of the screen $= 88.0\, cm$
$(i)$ Where will the image be formed if he shifts the candle towards the lens at a position of $31.0\, cm$?
$(ii)$ What will be the nature of the image formed if he further shifts the candle towards the lens?
$(iii)$ Draw a ray diagram to show the formation of the image in case $(ii)$ as said above.

Both a spherical mirror and a thin spherical lens have a focal length of $-15 \; cm$. What type of mirror and lens are they?

For what position of the object does a convex lens form an erect and virtual image?