Arrange the following electromagnetic radiations in decreasing order of their frequencies.

Question

Arrange the following electromagnetic radiations in decreasing order of their frequencies.

1. Gamma rays

2. Ultraviolet rays

3. Radio waves

4. X-rays

Select the correct answer from the code given below:

1. A. 1, 4, 3, 2
2. B. 4, 1, 2, 3
3. C. 1, 4, 2, 3 (Correct answer)
4. D. 4, 1, 3, 2

Correct Answer

Option C — 1, 4, 2, 3

Detailed Solution & Explanation

The correct answer is 1, 4, 2, 3.

Key Points

Arranging by decreasing frequency:

• 1. Gamma rays — the highest frequency and shortest wavelength.
• 4. X-rays
• 2. Ultraviolet rays
• 3. Radio waves — the lowest frequency and longest wavelength.
• The order is 1 → 4 → 2 → 3, option (c).

Additional Information

• The full electromagnetic spectrum in order of increasing wavelength (and therefore decreasing frequency and energy): Gamma rays → X-rays → Ultraviolet → Visible light → Infrared → Microwaves → Radio waves.
• All electromagnetic waves travel at the same speed in vacuum, about 3 × 10⁸ m/s, and are related by c = fλ, so frequency and wavelength are inversely proportional. Energy is given by E = hf, so higher frequency means higher energy.
• Visible light spans roughly 400-700 nm; within it the order VIBGYOR runs from shortest wavelength (violet) to longest (red).
• Uses: gamma rays — cancer therapy and sterilisation; X-rays — medical imaging; UV — sterilisation and vitamin D synthesis; infrared — remote controls and thermal imaging; microwaves — radar and cooking; radio waves — broadcasting and communication.