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NEET 2026
Exam
NEET
Year
2026
Subject
Physics
Chapter
Chapter

NEET 2026 · Physics · Chapter

In a Young's double slit setup, the slits are illuminated by a...

In a Young's double slit setup, the slits are illuminated by a white light source. Which colour of light will form the first-order bright fringe closest to the central white maximum on the viewing screen?

Options

  1. AViolet
  2. BYellow
  3. CRed
  4. DGreen

Correct answer

A. Violet

Step-by-step solution

The position of the nn-th order bright fringe from the central maximum in Young's double slit experiment is given by yn=nλDdy_n = \dfrac{n \lambda D}{d}.

For the first-order bright fringe, n=1n = 1, which gives y1=λDdy_1 = \dfrac{\lambda D}{d}.

The distance y1y_1 is directly proportional to the wavelength λ\lambda of the light.

Among the colours of visible light, violet has the shortest wavelength (λviolet<λgreen<λyellow<λred\lambda_{violet} < \lambda_{green} < \lambda_{yellow} < \lambda_{red}).

Since violet light has the minimum wavelength, its first-order bright fringe will be formed at the minimum distance from the central maximum. Therefore, violet will be closest to the central white maximum.

Answer: Violet
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