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.
📖 Key Definitions
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).
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.