White light passing through a prism is split into colours because
Correct answer: B. different wavelengths travel at different speeds in glass and so are refracted through different angles
- A. the prism adds colour to the light
- B. different wavelengths travel at different speeds in glass and so are refracted through different angles
- C. the glass absorbs some colours
- D. light slows down equally for all colours
Explanation
Dispersion arises because the refractive index of glass depends slightly on wavelength, being greatest for violet, which is therefore deviated most and red least. The prism separates colours already present in white light rather than creating them, as Newton demonstrated by recombining them with a second prism. The same effect produces a rainbow in water droplets.
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About Optics
Light is studied through reflection, refraction, dispersion, interference, diffraction and polarization, linking ray behavior with its wave nature. Questions may involve mirrors, lenses, optical instruments, refractive index and image formation, while geometrical optics deals with rays and wave optics explains effects such as interference and diffraction.
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