Q. Consider the following groups of electromagnetic waves arranged in increasing order of wavelength:

1. X-rays
2. Radio waves
3. Ultraviolet rays
4. Infrared rays

Which one of the following correctly represents the increasing order of their wavelengths?
Answer: X-rays < Ultraviolet rays < Infrared rays < Radio waves
Notes: X-rays have the shortest wavelengths (about 10⁻¹⁰ m), followed by ultraviolet rays (~10⁻⁸ m), infrared rays (~10⁻⁶ m), while radio waves possess the greatest wavelengths (ranging from meters to kilometers). Therefore, the correct sequence is: X-rays < Ultraviolet rays < Infrared rays < Radio waves.