Light numericals set 2

If the radius of curvature of a lens is 40 cm, then then the focal length of lens is

• 10

• 40

• 60

• 20

The refractive index of glass is 1.50, then the speed of light in glass Will be

• 6 X 10 power of 8 ms -1

• 4 X 10 power of 8 ms -1

• 2 X 10 power of 8 ms -1

• 1 X 10 power of 8 ms -1

An object is placed 15 cm from convex lens focal length is 10 cm, then the image distance is

• – 60 cm

• – 6 cm

• + 6 cm

• + 60 cm

Observe the given diagram, find the focal length of the convex lens?

• 30 cm

• 60 cm

• 45 cm

• 15 cm

If an object is placed 45 cm from a convex lens. The object placed at a distance 90 cm, then it’s focal length is

• + 30 cm

• – 30 cm

• + 10 cm

• – 10 cm

A converging lens has focal length of 15 cm . At what distance should the object be placed from the lens so that it forms an image at 30 cm from the lens

• + 60 cm

• – 30 cm

• – 60 cm

• + 30 cm

The object and image distance of a lens are – 40 cm and- 20 cm respectively then the magnification of lens is

• – 0.25

• + 0.25

• – 0.5

• + 0.5

The height of object and image distance are + 6 cm and+ 18 cm respectively, then it’s magnification is

• – 0.3 cm

• + 3 cm

• – 3 cm

• + 0.3 cm

If the focal length of concave lens is 40 cm, then the power of lens is

• – 0.025 D

• + 0.025 D

• – 2.5 D

• + 2.5 D

Power of lens is + 4.5 D, it’s focal length and the type of lens is

• + 0.22m, convex lens

• -0. 22 m, concave lens

• + 2 m, convex lens

• – 2 m, concave lens