The Electromagnetic Spectrum: Question 1

Worked solution

Step 1: Recall the full sequence of the electromagnetic spectrum

The full electromagnetic spectrum, in order of increasing wavelength (equivalently, decreasing frequency), is:

$\text{gamma rays} \to \text{X-rays} \to \text{ultraviolet} \to \text{visible light} \to \text{infrared} \to \text{microwaves} \to \text{radio waves}$

Gamma rays sit at the short-wavelength, high-frequency end; radio waves sit at the long-wavelength, low-frequency end.

Step 2: Pick out the four named regions in the correct order

The question only names four of these regions: gamma rays, visible light, infrared and radio waves. Reading them off the sequence above in the same left-to-right order gives:

$\text{gamma rays} \to \text{visible light} \to \text{infrared} \to \text{radio waves}$

This is increasing wavelength throughout: gamma rays have the shortest wavelength, then visible light, then infrared (longer wavelength than visible light), then radio waves (the longest wavelength of the four).

Step 3: Match to the correct option

This order (gamma rays, visible light, infrared, radio waves) is exactly option B.

Why the other options are wrong

Final answers

• Increasing wavelength order: gamma rays, visible light, infrared, radio waves, option B.