The Electromagnetic SpectrumOxford AQA IGCSE Physics: Flashcards

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What type of wave are electromagnetic waves?

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What type of wave are electromagnetic waves?: Transverse waves that transfer energy from a source to an absorber.
Do electromagnetic waves need a medium to travel?: No — they can travel through a vacuum (space), unlike sound waves.
List the seven regions of the EM spectrum in order of increasing frequency.: Radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, gamma rays.
What determines the colour we see in visible light?: The wavelength of the light — different wavelengths appear as different colours.
Which types of surfaces are the best absorbers and emitters of infrared radiation?: Darker, matt surfaces.
Which types of surfaces are good reflectors of infrared radiation?: Lighter, shiny surfaces (poor absorbers/emitters).
Define black-body radiation.: The range of electromagnetic radiation emitted by an object at a particular temperature.
Give a use of microwaves.: Mobile phone communication and satellite TV.
Give a use of ultraviolet radiation.: Security marking.
Give a use of gamma rays.: Sterilising medical instruments and killing bacteria in food.
Name a hazard of ultraviolet radiation.: Skin cancer and blindness.
Name a hazard of gamma rays.: Genetic mutations.
Why are X-rays useful for imaging bone fractures?: X-rays are absorbed by bone/metal but transmitted by healthy soft tissue, creating a contrast image on photographic film or a detector.
Why must exposure to ionising EM radiation be monitored and minimised?: Because high-energy ionising radiation (UV, X-rays, gamma rays) can damage living cells and DNA.