Q. Consider the following statements regarding the propagation of red and blue light:

1. In vacuum, both red and blue coloured light travel at the same speed.
2. In glass, the speed of red coloured light is greater than that of blue coloured light.

Which of the above statements is / are correct?
Answer: Both 1 and 2 are correct
Notes: In vacuum, light of all wavelengths—including red and blue—travels at the same speed (the speed of light, c ≈ 3 × 10⁸ m/s). In glass, the refractive index is higher for blue light (shorter wavelength), so blue light slows more than red light. Hence, red light travels faster than blue light in glass. Both statements are correct.