5.4 UNDERSTANDING LENSES

Images formed by convex lenses

u>2f

i)real

ii)inverted

iii)diminshed

u=2f

i)real

ii)inverted

iii)same size

f<u<2f

i)real

ii)inverted

iii)magnified

u=f

i) infinity

u<f

i)virtual

ii)upright

iii)magnified

The differences between microscope and telescope

MICROSCOPE

Application : to view very small objects like microorganisms

A magnifying glass consits of a converging lens.
The object must be mplaced at a distance less than f.
Greater magnification can be obtained by using a lens which has short focal length.

TELESCOPE

Application : view very distant objects like the planets and the stars

The astronomical telescope consists of 2 converging lenses.
The objective lens has focal length and the eye lens also has focal length , where the focal length of objective lens more than focal length of eye lens.