Linked fields
Changing electric and magnetic fields can form a propagating disturbance. Electromagnetic waves do not require air or another mechanical medium, allowing sunlight to cross space. In physics, “light” can include electromagnetic radiation outside the range visible to human eyes.
Frequency, wavelength and the spectrum
Wavelength describes a spatial repetition distance and frequency the number of cycles per second; in vacuum their product is the speed of light. Radio, microwave, infrared, visible, ultraviolet, X-ray and gamma-ray are names for different ranges of this spectrum.
Theory tested by experiment
Maxwell’s theory connected electricity, magnetism and light. Hertz later generated and detected radio waves and investigated their propagation. Together these developments established physical connections across spectral ranges and supported later communications and measurement technologies.
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Observing in different spectral ranges
Matter absorbs, emits and reflects radiation selectively, while Earth’s atmosphere limits which wavelengths reach the ground. Different detectors and space-based instruments therefore observe the same object in different bands, often revealing different physical processes rather than interchangeable views.