You are given a convex lens of focal length 30 cm. At what distance from the lens should you hold a candle flame to observe.
(a) a real and magnified image of the flame ? (b) a virtual and magnified image of the flame?
( c) a real, inverted and smaller image of the flame?

Explanation

Here, `f=30 cm`.
(a) To obtain, a real and magnified image,object must lie between f and `2f` i.e., distance of flame from the lens should lie between `30` and `60 cm`.
( b) To obtain a virtual image, object must lie between principal focus and optical centre of the lens i.e., distance of flame from the lens should lie between 0 and `30 cm`.
(c ) To obtain, a real , inverted and smaller image of the flame, object must lie beyond `2 f` of the lens, i.e., the flame should be held at a distance be held at a more than `60 cm` from the lens.