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Asked: 2025-10-02T14:00:54+00:00 In:

A person allowed a narrow beam of white light from the sun to enter a dark room through a small aperture and placed a glass prism in its path in such a manner that the beam falls on the face AB of the prism as shown in the figure. A screen S is placed on the other side of the prism, facing AC. On turning the prism slowly, a beautiful band of colours is obtained on the screen. It is the spectrum of sunlight. (a) Name the phenomenon due to which a prism splits the incident white light into a band of colours. (b) State the reason of getting a band of seven colours in the above case.

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A person allowed a narrow beam of white light from the sun to enter a dark room through a small aperture and placed a glass prism in its path in such a manner that the beam falls on the face AB of the prism as shown in the figure. A screen S is placed on the other side of the prism, facing AC. On turning the prism slowly, a beautiful band of colours is obtained on the screen. It is the spectrum of sunlight. (a) Name the phenomenon due to which a prism splits the incident white light into a band of colours. (b) State the reason of getting a band of seven colours in the above case.

The phenomenon is called dispersion of light. White light is a mixture of seven colours. Each colour has a different wavelength and, hence, is refracted (bent) by the glass prism through different angles, resulting in a band of seven distinct colours.

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a narrow beam of white lightclass 10 science half yearly 2025phenomenon due to which a prism splits
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    1. A person allowed a narrow beam of white light from the sun to enter a dark room through a small aperture and placed a glass prism in its path in such a manner that the beam falls on the face AB of the prism as shown in the figure. A screen S is placed on the other side of the prism, facing AC. On turning the prism slowly, a beautiful band of colours is obtained on the screen. It is the spectrum of sunlight. (a) Name the phenomenon due to which a prism splits the incident white light into a band of colours. (b) State the reason of getting a band of seven colours in the above case.

      (a) The phenomenon is called dispersion of light.

      (b) White light is a mixture of seven colours. Each colour has a different wavelength and, hence, is refracted (bent) by the glass prism through different angles, resulting in a band of seven distinct colours.

      (c) To show recombination of spectrum of white light, Newton used two prisms. The first prism disperses white light into seven colours. When this spectrum is passed through a second, inverted prism, it recombines the seven colours back into white light.

      Labelled Ray Diagram:

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