Question

The image of a candle flame formed by a lens is obtained on a

screen placed on the other side of the lens. If the image is three

times the size of the flame and the distance between lens and

image is 80 cm, at what distance should the candle be placed

from the lens? What is the nature of the image at a distance of

90 cm and the lens?​

Answer 1

Answer:

Magnification is 3 times and image distance v=80cm

Magnification =

u

v

Or,3=

u

80cm

Or, u=

3

80cm

since,object distance is taken as negative; as per sign convention so,

or, u=−

3

80cm

Nature of image: since image is formed on the other side of lens hence it is a real image and inverted image.

Nature of Lens: Enlarged image is formed by convex lens and not by concave lens, so it is a convex lens.