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Dispersion of Light Projectee - Nishtha Pathak Class - 10 th ‘B’

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What is Dispersion? <ul><li>The splitting up of white light into its seven constituent </li></ul><ul><li>colours on passing through a transparent medium (like </li></ul><ul><li>glass prism) is called dispersion of light. </li></ul>

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Cause of Dispersion <ul><li>The dispersion of white light occurs because colours of </li></ul><ul><li>white light travel at different speeds through the glass </li></ul><ul><li>prism. The amount of refraction depends on the speed </li></ul><ul><li>of coloured light in glass. Now, since the different </li></ul><ul><li>colours travel at different speeds, they are refracted by </li></ul><ul><li>different angles on passing through the glass prism. </li></ul><ul><li>So, when white light consisting of seven colours falls </li></ul><ul><li>on a glass prism, each colour in it is refracted by a </li></ul><ul><li>different angle, with a the result that seven colours </li></ul><ul><li>spread out to form a spectrum. </li></ul>

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Spectrum <ul><li>The band of seven colours formed on a white screen, </li></ul><ul><li>when a beam of white light is passed through a glass </li></ul><ul><li>prism, is called spectrum of white light. The seven </li></ul><ul><li>colours of the spectrum are: Violet, Indigo, Blue, </li></ul><ul><li>Green, Yellow, Orange, and Red. It can be denoted by </li></ul><ul><li>the word VIBGYOR. </li></ul>

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Newton’s Experiment <ul><li>Newton performed an experiment to show that white </li></ul><ul><li>light consist of colours. A white light ray is passed </li></ul><ul><li>through a prism to split it into the colours of the </li></ul><ul><li>spectrum. The different coloured light is allowed to </li></ul><ul><li>pass through an identical prism kept in inverted </li></ul><ul><li>position. The light emerging out of second prism was </li></ul><ul><li>found to be white indicating that the light ray consist of </li></ul><ul><li>colours. </li></ul>

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Rainbow <ul><li>A rainbow is a natural spectrum appearing in the sky </li></ul><ul><li>after a rain shower. It is caused by dispersion of </li></ul><ul><li>sunlight by tiny water droplets present in the </li></ul><ul><li>atmosphere. A rainbow is always formed in a direction </li></ul><ul><li>opposite to that of the Sun. The water droplets acts </li></ul><ul><li>like a small prism. They refract and disperse the </li></ul><ul><li>incident sunlight, then reflect it internally, and finally </li></ul><ul><li>refract it again when it comes out of the raindrop. Due </li></ul><ul><li>to the dispersion of light and internal reflection, </li></ul><ul><li>different colours reach the observer’s eye. </li></ul>

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Lets Find Out More Facts

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What is the range of visible light? <ul><li>Range of visible light – 0.4 microns to 0.7 microns. </li></ul><ul><li>Visible light has a large number of radiations having wavelengths ranging from 0.4 microns to 0.7 microns. That is, red light has a large wavelength compared to violet light. </li></ul>

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Which component deviates maximum? <ul><li>The violet colour has the minimum speed in prism, so the violet colour is deviated the maximum. </li></ul>

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Which component deviates minimum? <ul><li>The red colour has the maximum speed in prism, so the red colour is deviated the minimum. </li></ul>

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Rate of photosynthesis? <ul><li>Wavelength of the component that increases the rate of photosynthesis - 0.7 microns. </li></ul><ul><li>The rate of photosynthesis is the most in the presence of red light. </li></ul>

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Which colour doesn’t affect the rate of photosynthesis? <ul><li>Component which does not affect the rate of photosynthesis - green light. </li></ul><ul><li>The rate of photosynthesis is zero in the presence of green light. </li></ul>

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What is the nature of the spectrum emerging out of the first prism? <ul><li>Nature of the spectrum emerging out of the first prism - a band or spectrum of seven colours is obtained. </li></ul><ul><li>The prism splits white light into seven colours. </li></ul>

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What is the nature of the spectrum emerging out of the second prism? <ul><li>Nature of the spectrum emerging out of the second prism – white light is obtained. </li></ul><ul><li>The seven colours of the visible spectrum combine to form white light. </li></ul>