Electromagnetic spectrum: The family of transverse waves that all travel at 3 × 10⁸ m/s in a vacuum, ranging from long-wavelength radio waves to short-wavelength gamma rays.
Ionising radiation: Radiation with enough energy to remove electrons from atoms, potentially damaging DNA. UV, X-rays, and gamma rays are ionising.
Infrared radiation: EM waves with wavelengths longer than visible light, emitted by all objects as thermal radiation. Used in thermal cameras and remote controls.
Ultraviolet (UV): EM waves with wavelengths shorter than visible light. Causes sunburn and skin cancer by ionising skin cells; also used in sterilisation.
Speed of light (c): The speed of all EM waves in a vacuum = 3 × 10⁸ m/s (300,000,000 m/s).
This definitions covers Key Definitions within Electromagnetic Spectrum for GCSE Physics. Revise Electromagnetic Spectrum in Waves for GCSE Physics with 17 exam-style questions and 15 flashcards. This is a high-frequency topic, so it is worth revising until the explanation feels precise and repeatable. It is section 7 of 13 in this topic. Make sure you can use the exact wording confidently, because definition marks are often lost through vague language.
Practice questions for Electromagnetic Spectrum
What is the speed of all electromagnetic waves in a vacuum?
Explain the potential dangers of ultraviolet radiation to humans.