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 is 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 options given below:
A. Speed of light in vacuum is dependent on the direction of propagation.
B. Speed of light in a medium is 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 options given below:
- A.A and C only
- B.B and C only
- C.B and D only
- D.C and D only
Show answer and solution
Correct option: D
Solution
C is correct because it is a foundational postulate of special relativity — the speed of light in vacuum is always c regardless of the motion of the source. D is correct because the speed of light in a medium depends on the medium's refractive index (a property of the medium and wavelength), not on the intensity of the light wave. A is wrong because light in vacuum is isotropic — speed is the same in all directions. B is wrong because the speed of light in a medium does depend on wavelength (this is dispersion — different wavelengths travel at different speeds, which is why prisms split white light).
[JEE Main 2023 · 29 Jan · Shift 1]