HUMAN EYE & COLOURFUL WORLD

The danger signals installed at the top of tall buildings are red in colour. These can be easily seen from a distance because among all other colours, the red light

• is scattered the most by smoke or fog

• is scattered the least by smoke or fog

• is absorbed the most by smoke or fog

• moves fastest in air

The splitting of white light into different colours on passing through a prism is called

• Reflection

• Refraction

• Dispersion

• Deviation

The image shows a light ray incident on a glass prism.

The various angles are labelled in the image. Which angle shows the angle of incidence and angle of refraction, respectively?

• A and D

• B and E

• C and F

• D and F

The deflection of light by minute particles and molecules of the atmosphere in all directions is called ____________ of light.

• dispersion

• scattering

• interference

• Tyndall effect

Which of the following phenomena contributes significantly to the reddish appearance of the sun at sunrise or sunset?

• (a) Dispersion of light

• (b) Scattering of light

• (c) Total internal reflection of light

• (d) Reflection of light from the earth

Why do stars appear to twinkle at night?

• (a) because the light of stars travels in different medium

• (b) because the distance of star varies when earth rotates

• (c) because the star changes its position relative to earth

• (d) because the atmosphere reflects the light at different angles

When white light enters a prism, it gets split into its constituent colours. This is due to

• (a) different refractive index for different wavelength of each colour

• (b) each colour has the same velocity in the prism.

• (c) prism material has high density.

• (d) Scattering of light

When white light enters a glass prism from air, the angle of deviation is least for

• (a) blue light

• (b) yellow light

• (c) violet light

• (d) red light

Which option justifies that the Sun appears red at sunrise and sunset?

• (a) red scatters highest by the atmosphere

• (b) the distance between the sun and earth reduces

• (c) red has high wavelength, so it travels longer distance

• (d) the white light disperses into seven colours, only red enters the atmosphere

The image shows the dispersion of the white light in the prism.

What will be the colours of the X, Y and Z?

• (a) X: red; Y: green; Z: violet

• (b) X: violet; Y: green; Z: red

• (c) X: green; Y: violet; Z: red

• (d) X: red; Y: violet; Z: green