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NATURE OF IMAGE FORMED BY CONVEX LENS:
 The nature of image formed by a convex lens depends on the position of the object, that is, the
distance between the object and the lens.
 When the object is placed far from lens, the image formed is small, inverted and real image.
 When the object is placed at the centre of curvature, the image formed is of same size as that of
the object.
 When the object is placed very close to lens, the nature of image formed is virtual, erect and
enlarged.

POSITION OF OBJECT POSITION OF IMAGE NATURE OF IMAGE
At infinity At focus Real, inverted and
diminished in size

Beyond 2F1 Between F2 and 2F2 Real, inverted and
diminished in size
At 2F1 At 2F2 Real, inverted and same
size as that of the object
Between F1 and O On the same side as that Virtual, erect and enlarged
of the object
Between F1 and 2F1 Beyond 2F2 Real, inverted and
enlarged
At focus At infinity Real, inverted and
enlarged

USES OF CONVEX LENS
 Used in spectacles for long sightedness.
 Used as magnifying glass.
 Used in microscope and telescope.

CONCAVE LENS:
The lens which is thinner at the middle but thicker at the edges is known as concave lens.
It is diverging in nature as, it diverges the light rays falling on it.