Chapter 6 (Chapter End Test)

The unit of power of a lens is ........ .

• watt

• kilo watt

• mega watt

• dioptre

Reciprocal of the focal length in metres is known as the ....... of the lens.

• focus

• power

• centre

• double focus

The focal length of a lens is given as ........ .

• f = 1/u + 1/v

• f = u + v

• f = 1/u - 1/v

• 1/f = 1/u + 1/v

The object u is 2f, a convex len uses as in a ........ .

• camera

• projector

• photocopier

• spectacle

The ...... image cannot be formed on a screen.

• real

• virtual

• inverted

• non of these

The lens in your eyes are ....... .

• concave lens

• converging lens

• diverging lens

• diverging meniscus

The magnification of a concave lens is always......... .

• m = +1

• m =+2

• m <+1

• m > +1

The power of a lens of focal length + 10 cm is ....... .

• 1 D

• 10 D

• 100 D

• Non of these

Both real and virtual images can be formed by a ........ lens.

• convex

• concave

• diverging

• plano concave

The object distance is at infinity, a convex lens used as in a ....... .

• camera

• magnifying glass

• object lens of a telescope

• microscope