Question

Arrange the following type of electromagnetic waves according to increasing order of their wavelengths :
A. Gamma rays
B. Infrared rays
C. Visible rays
D. Ultraviolet rays
E. Radio waves
Choose the correct answer from the options given below :

• A. A, C, D, E, B
• B. A, B, C, D, E
• C. A, D, C, B, E
• D. B, D, A, E, C

Hint:

A classic mnemonic to remember the spectrum from longest to shortest wavelength (Reverse of this question): Roman Men Invented Very Unusual X-ray Guns (Radio, Microwave, IR, Visible, UV, X-Ray, Gamma).

Answer 1

The Correct Option is C

Step 1: Concept:
The problem requires ordering distinct regions of the electromagnetic (EM) spectrum based on their wavelength ($\lambda$).

Step 2: Key Formula or Approach:
The electromagnetic spectrum follows an inverse relationship between energy/frequency and wavelength: higher energy means shorter wavelength ($E = hc/\lambda$).
The general order of the EM spectrum from highest energy shortest wavelength to lowest energy longest wavelength is:
Gamma Rays $\rightarrow$ X-Rays $\rightarrow$ Ultraviolet (UV) $\rightarrow$ Visible Light $\rightarrow$ Infrared (IR) $\rightarrow$ Microwaves $\rightarrow$ Radio Waves.

Step 3: Step-by-step Explanation:

• We need to arrange them in increasing order of wavelength (shortest to longest).

• A. Gamma rays: Highest energy, shortest wavelength ($< 0.01 \text{ nm}$). (Position 1)

• D. Ultraviolet rays: Lower energy than Gamma, shorter than visible ($10 - 400 \text{ nm}$). (Position 2)

• C. Visible rays: Intermediate energy and wavelength ($400 - 700 \text{ nm}$). (Position 3)

• B. Infrared rays: Lower energy than visible, longer wavelength ($700 \text{ nm} - 1 \text{ mm}$). (Position 4)

• E. Radio waves: Lowest energy, longest wavelength ($> 1 \text{ m}$). (Position 5)

• The sequence from shortest to longest wavelength is: Gamma (A) $<$ UV (D) $<$ Visible (C) $<$ IR (B) $<$ Radio (E).

Step 4: Final Answer:
The correct increasing order is A, D, C, B, E, which matches option (C).