Consider the following statements about visible light, UV light and X-

Consider the following statements about visible light, UV light and X-rays :

  • 1. The wavelength of visible light is more than that of X-rays.
  • 2. The energy of X-ray photons is higher than that of UV light photons.
  • 3. The energy of UV light photons is less than that of visible light photons.

Which of the statements given above is/are correct?

1, 2 and 3
1 and 2 only
2 and 3 only
1 only
This question was previously asked in
UPSC NDA-2 – 2018
Statements 1 and 2 are correct, while statement 3 is incorrect.
The electromagnetic spectrum is ordered by wavelength and energy/frequency. Wavelength and energy/frequency are inversely related (Energy E = hc/λ, where h is Planck’s constant, c is the speed of light, and λ is wavelength). Lower wavelength corresponds to higher energy/frequency. The order of these radiations by increasing wavelength (decreasing energy/frequency) is X-rays < UV light < Visible light.
1. Wavelength of visible light is more than that of X-rays: Correct, as visible light is further towards the longer wavelength end of the spectrum compared to X-rays.
2. The energy of X-ray photons is higher than that of UV light photons: Correct, as X-rays are to the higher frequency/energy side of UV light in the spectrum.
3. The energy of UV light photons is less than that of visible light photons: Incorrect, as UV light is to the higher frequency/energy side of visible light. UV photons have higher energy than visible light photons.