Page 18 - 7-Sci-9 Dispersion of Light

9. Dispersion of Light eLearn.Punjab

Animation 9.10: Rainbow
Source and Credit: University of Utah

Key Points

• When light passes from a transparent medium to another, it changes speed and bends. This
bending of light is called refraction.

• Refraction causes images to form in our eyes.
• When light passes through a prism, it refracts and bends at an angle. A prism can split white

light into its component colours.
• Red, orange, yellow, green, blue, indigo and violet are the component colours of white light.
• The band of seven colours of light is called the spectrum of light.
• A rainbow disc has all the seven colours of light. When it is spinned, white disc is seen.
• Red, blue and green are three primary colours of light. Primary colours combine to make

secondary colours of light.
• The colour of an object is the colour of light it reflects. A red flower reflects red colour and

appears red. A white surface reflects all the colours of light and appears white. A black surface
reflects no colour.

Questions

1. Complete each of the following sentences by writing the correct term.
i. They can carry thousands of phone conversations at the same time _______
ii. The bending of light, when it enters from one medium to another _______
iii. The angle of incidence at which maximum refraction occurs _______
iv. The ratio of the speed of light in vacuum to its speed in another medium _______
v . The splitting of white light into its component colours

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