In visible light, orange differs from violet as they have

The correct answer is Option (3) → different frequencies and different wavelengths

All colours of light travel with the same speed \( c \) in vacuum, and for every colour \( c = \nu\lambda \). The colour of light is fixed by its frequency: orange has a lower frequency than violet.

Since \( c \) is the same, a different frequency means a different wavelength as well (\( \lambda = c/\nu \)). Orange, with the lower frequency, has the longer wavelength.

Option (1) same frequencies and different wavelengths — Incorrect. The same frequency would mean the same colour.

Option (2) same frequencies and same wavelengths — Incorrect. The same frequency and wavelength would make the two lights identical.

Option (3) different frequencies and different wavelengths — Correct. Different colours have different frequencies, and \( \lambda = c/\nu \) then gives different wavelengths.

Option (4) different frequencies and same wavelengths — Incorrect. With the same speed \( c \), different frequencies cannot have the same wavelength.

Note: This question is from the pre-rationalised NCERT book (2022-23). The topic was removed from the latest NCERT book (2026-27), but it is still in the CUET 2026 syllabus, so do not skip it.

NCERT (Pre-rationalised edition, 2022-23):
Dispersion by a Prism – “… We now know that colour is associated with wavelength of light. In the visible spectrum, red light is at the long wavelength end (~700 nm) while the violet light is at the short wavelength end (~ 400 nm).”