What is dispersion of white light? Is it possible to recombine the lights of seven colours to obtain the white light again? [3 marks]

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Solution

Dispersion is the splitting up of white light into seven colours on passing through a transparent medium like a glass prism. [0.5 marks]

When a white light beam is passed through a prism, a band of seven colours are formed which is known as a spectrum of white light. The seven colours in the spectrum are red, orange, yellow, green, blue, indigo and violet respectively. [0.5 marks]

If one more prism is arranged in opposite manner, then the dispersed colours will merge into white light beam again. All the colours will be arranged as violet, indigo, blue, green, yellow, orange and red from down to up. When these passes from the second prism, all join together and gives a white light as shown in the figure. [2 marks]

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Similar questions

When a beam of white light is passed through a prism, it splits to form lights of seven colours. Is it possible to recombine the lights of seven colours to obtain the white light again ? Explain your answer.

State whether the following statement is True or False.

It is not possible to recombine the lights of seven colours to obtain the white light

Q. Dispersion of light is the splitting of white light into its seven constituent colours.

Assertion(A): A rainbow is formed when white light is incident on raindrops.

Reason(R): White light contains seven colours and it undergoes dispersion inside a raindrop.

Is it true that dispersion of light also takes place in parallel sided glass slab but not to that extent as in prism .

I read in book that :

Dispersion takes place inside the slab, but, since the rays which emerge from the slab all run parallel to one another, the dispersed colours recombine to form white light again, and no dispersion is observed except at the very edges of the beam.
It follows that the dispersion of white light through a parallel-sided glass slab is not generally a noticeable effect.

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