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Q4 (CDS-II/2014) Science & Technology › Basic Science (Physics, Chemistry, Biology) › Geometrical optics Answer Verified

In the phenomenon of dispersion of light, the light wave of shortest wavelength is

Result
Your answer: —  Â·  Correct: B
Explanation

In the phenomenon of dispersion, the refractive index of a medium is wavelength-dependent. For transparent materials like glass, the refractive index increases as the wavelength of incident light decreases [2]. Since the refractive index is defined as the ratio of the speed of light in a vacuum to its speed in the medium, a higher refractive index for shorter wavelengths (like violet) implies that these waves travel more slowly in the medium compared to longer wavelengths [1]. According to Snell's Law, a higher refractive index results in a greater degree of bending or deflection. Consequently, light waves with the shortest wavelengths are slowed down the most and refracted the most when passing through a dispersive medium [2]. This differential slowing and bending causes white light to split into its constituent spectral colors.

Sources

  1. [2] https://www.ncbi.nlm.nih.gov/books/NBK592413/
  2. [1] Science , class X (NCERT 2025 ed.) > Chapter 9: Light – Reflection and Refraction > 9.3.2 The Refractive Index > p. 148
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