Among the following types of electromagnetic radiation, which one has the maximum wavelength (that is, the lowest frequency and energy)?

Introduction / Context:
The electromagnetic spectrum covers a wide range of radiation types, from very high energy gamma rays to very low energy radio waves. Each region of the spectrum can be described by its typical range of wavelength, frequency and photon energy. Many basic physics and chemistry questions ask you to compare these forms of radiation. Knowing which part of the spectrum has the longest wavelength helps build a clear mental picture of how different electromagnetic waves relate to each other.

Given Data / Assumptions:

• The options given are ultraviolet, radio waves, X rays and infrared radiation.
• We are asked which of these has the maximum wavelength.
• We assume the standard ordering of the electromagnetic spectrum as taught in school level physics.
• There are no special conditions that would alter the usual wavelength ranges.

Concept / Approach:
In the electromagnetic spectrum, wavelength, frequency and energy are related. As wavelength increases, frequency and photon energy decrease. Starting from the shortest wavelengths, the order is gamma rays, X rays, ultraviolet, visible light, infrared, microwaves and radio waves. Therefore, among the four choices given, radio waves lie at the long wavelength end of the spectrum and must have the largest wavelength. Ultraviolet and X rays have much shorter wavelengths, while infrared lies between visible light and microwaves, still shorter than radio waves.

Step-by-Step Solution:
Step 1: Recall the standard order of electromagnetic radiation when arranged by increasing wavelength: gamma rays, X rays, ultraviolet, visible, infrared, microwaves, radio waves.Step 2: Identify the positions of the given options in this sequence.Step 3: X rays are near the short wavelength, high energy end of the spectrum, just after gamma rays.Step 4: Ultraviolet radiation has shorter wavelengths than visible light but longer than X rays.Step 5: Infrared radiation has longer wavelengths than visible light but shorter than microwaves and radio waves.Step 6: Radio waves occupy the region with the greatest wavelengths and lowest frequencies among the options listed.Step 7: Therefore, radio waves have the maximum wavelength among the given types of radiation.

Verification / Alternative check:
You can also check using frequency. Radio stations broadcast using waves whose frequencies are measured in kilohertz or megahertz, which are much lower than the frequencies of visible or ultraviolet light. Because the speed of light in a vacuum is essentially constant, lower frequency implies longer wavelength. In contrast, X rays and ultraviolet radiation are associated with very high frequencies and therefore very short wavelengths. This confirms that radio waves have the longest wavelength among the options given.

Why Other Options Are Wrong:
Option a, ultraviolet, lies between X rays and visible light and has shorter wavelengths than both visible and infrared radiation. Option c, X rays, are even more energetic than ultraviolet and have very short wavelengths. Option d, infrared, has longer wavelengths than visible light but is still shorter in wavelength than radio waves. Hence none of these can match the extremely long wavelengths characteristic of radio waves, which can span from meters to many kilometres.

Common Pitfalls:
Many students remember the order of colours in visible light but struggle with the full spectrum. A common error is to mix up infrared and ultraviolet, or to assume that infrared has the longest wavelength simply because it is associated with heat. Another pitfall is focusing on energy instead of wavelength and forgetting the inverse relationship. To avoid these mistakes, memorize a simple mnemonic for the entire spectrum and repeatedly visualise the progression from gamma rays to radio waves. Remember that radio waves always sit at the long wavelength end of this sequence.

Final Answer:
Among the listed types of electromagnetic radiation, radio waves have the maximum wavelength.