The electromagnetic spectrum encompasses the entire range of electromagnetic radiation, from the longest radio waves to the shortest gamma rays. All of these waves travel at the speed of light in a vacuum, but they differ in wavelength, frequency, and energy.
The spectrum includes, in order of increasing frequency and energy (and decreasing wavelength):
- Radio Waves – Used in communication (radio, TV, mobile phones); have the longest wavelengths (meters to kilometers).
- Microwaves – Used in cooking and radar; wavelengths range from millimeters to centimeters.
- Infrared (IR) – Experienced as heat; used in night vision and thermal imaging.
- Visible Light – The tiny portion of the spectrum visible to the human eye; spans wavelengths from about 400–700 nanometers.
- Ultraviolet (UV) – Higher energy than visible light; can cause sunburn and is used in sterilization.
- X-Rays – Penetrate soft tissues and are used in medical imaging.
- Gamma Rays – Highest energy and frequency; emitted by radioactive substances and cosmic events; used in cancer treatment and astrophysics.
Each part of the electromagnetic spectrum has unique interactions with matter, making it useful in various fields like astronomy, medicine, communications, and physics.
Understanding the electromagnetic spectrum is crucial for:
- Designing technologies from radios to X-ray machines,
- Exploring the universe across different wavelengths (e.g., radio telescopes, gamma-ray observatories),
- Studying the fundamental nature of light and energy.