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प्रश्न
How could you show that the colours of the spectrum combine to give white light?
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उत्तर
We know that a spectrum of colours is formed when a beam of white light is passed through a transparent glass prism. These colours can be recombined to give white light again. This is achieved by placing another glass prism upside down behind the first prism. A patch of white light is obtained on a screen placed behind the second prism because the refraction produced by the second prism is equal and opposite to the refraction produced by the first prism.
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संबंधित प्रश्न
In the following diagram, the path of a ray of light passing through a glass prism is shown:
In this diagram the angle of incidence, the angle of emergence and the angle of deviation respectively are (select the correct option):
(A) X, R and T
(B) Y, Q and T
(C) X, Q and P
(D) Y, Q and P
Describe an activity to show that colours of white light splitted by a glass prism can be recombined to get white light by another identical glass prism. Also draw ray diagram to show the recombination of the spectrum of white light.
State the cause of dispersion of white light passing through a glass prism. How did Newton show that white light of sun contains seven colours using two identical glass prisms. Draw a ray diagram to show the path of light when two identical glass prisms are arranged together in inverted position with respect to each other and a narrow beam of white light is allowed to fall obliquely on one of the focus of the first prism.
Define the term dispersion of white light.
As light rays emerge from a glass prism into air, are they refracted towards or away from the normal?
In the figure given alongside, a narrow beam of white light is shown to pass through a triangular glass prism. After passing through the prism, it produces a spectrum YX on the screen.
Why do different colours of white light bend through different angles with respect to the incident beam of light?
Draw a diagram to show the refraction of light through a glass prism. On this diagram, mark
(i) incident ray
(ii) emergent ray, and
(iii) angle of deviation.
The speed of light in air or vacuum is
Which is optically denser: water or air? Give reason
Explain briefly, with the help of a neat labelled diagram, how white light gets dispersed by a prism. On which surface of a prism, there is both dispersion and deviation of light, and on which surface of the prism, there is only deviation of light ?
Complete the ray diagram given below to show the nature of light produced on the screen.
While performing the experiment to trace the path of a ray of light passing through a glass prism, four students marked the incident ray and the emergent ray in their diagrams in the manner shown below. 
(A) I
(B) II
(C) III
(D) IV
Differentiate between a glass slab and a glass prism.
What is the cause of the dispersion of white light through a glass prism? Draw a ray diagram to show the path of light when two identical glass prisms are arranged together in an inverted position with respect to each other and a narrow beam of white light is allowed to fall obliquely on one of the faces of the prisms.
Write three conditions necessary to obtain a pure spectrum on a screen. Name the instrument in which the conditions stated by you are fulfilled.
The splitting of white light into its component colours is called ____________.
The periscope is an optical device with a polished surface that reflects the light falling on it.
Observe the given diagram and answer the questions:
- Name the process shown in the figure.
- Name the colour that deviates the most.
- Name the colour that deviates the least.
- Name any one phenomenon in nature which is based on the above process.
- Define ‘spectrum’.
