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JEE Main · 2023 · 29 Jan 2023 · Shift 1 · EM Waves

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Which of the following are true?
(A) Speed of light in vacuum is dependent on the direction of propagation.
(B) Speed of light in a medium in independent of the wavelength of light.
(C) The speed of light is independent of the motion of the source.
(D) The speed of light in a medium is independent of intensity.

Choose the correct answer from the option given below :
  1. (A)A and C only
  2. (B)B and D only
  3. (C)B and C only
  4. (D)C and D only✓ Correct

Answer: (D)

Solution

The speed of light in vacuum is the same in every direction, so a direction dependence is wrong. In a material medium the speed depends on wavelength, which is exactly why a prism disperses white light, so independence of wavelength is wrong. The speed of light is independent of the motion of the source, a postulate of special relativity, and in a medium it is fixed by the refractive index and is unaffected by the intensity. The correct statements are that the speed is independent of the motion of the source and independent of the intensity.

JEE Main · 2023 · 29 Jan 2023 · Shift 1 · Single correct option

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