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Light and the electromagnetic spectrum

Edexcel GCSE PhysicsTopic 5 of 1524 lessons

Revision notes for Light and the electromagnetic spectrum in Edexcel Physics (1PH0). Every lesson in BrainCake comes with R.E.C.I.P.E. recall steps, a quick check and spaced reviews.

  1. Reflection, refraction and total internal reflectionWhen light hits a boundary it can be reflected.
  2. Specular and diffuse reflectionThe law of reflection applies to every ray of light that hits a surface.
  3. Colour, absorption and filtersWhite light is a mixture of all the colours of the visible spectrum.
  4. Power, focal length and shape of a lensA converging lens refracts parallel rays so that they meet at the principal focus.
  5. Converging and diverging lensesBoth types of lens work by refraction.
  6. Real and virtual images from lensesA real image forms where light rays actually meet.
  7. All electromagnetic waves are transverse and travel at the same speed in a vacuumElectromagnetic (EM) waves are transverse waves.
  8. Electromagnetic waves transfer energy from source to observerAll EM waves transfer energy from a source to an observer.
  9. Core Practical: Investigating refraction in rectangular glass blocksIn this practical you investigate how light, an EM wave, is refracted when it passes into and out of a rectangular glass block.
  10. The main groupings of the electromagnetic spectrumThe electromagnetic spectrum is the family of all EM waves.
  11. The electromagnetic spectrum is continuousThe electromagnetic spectrum is continuous.
  12. Our eyes detect only a limited range of frequenciesOur eyes can only detect a limited range of the frequencies of electromagnetic radiation.
  13. Absorption, transmission, refraction and reflectionWhen an electromagnetic wave meets a substance, one of four things can happen.
  14. Speed of electromagnetic waves in different substancesAll electromagnetic waves travel at the same speed in a vacuum, 3.0 × 108 m/s.
  15. All bodies emit radiationEvery object, whatever its temperature, emits electromagnetic radiation.
  16. Constant temperature: power in equals power outAn object gains energy when it absorbs radiation and loses energy when it emits radiation.
  17. Radiating less or more than is absorbedIf an object's average radiated power is different from its average absorbed power, its temperature must change.
  18. Earth's temperature and the radiation balanceThe Earth absorbs radiation from the Sun, mostly visible light, and emits its own radiation into space, mostly infrared.
  19. Core practical: surfaces and thermal radiationEvery object gives out infrared radiation, and every object absorbs it from its surroundings.
  20. Danger of electromagnetic waves and frequencyThe potential danger of an electromagnetic wave increases as its frequency increases.
  21. Harmful effects of excessive exposure to radiationElectromagnetic radiation can harm people if they are exposed to too much of it.
  22. Uses of electromagnetic radiationEach part of the electromagnetic spectrum has its own uses.
  23. Radio waves and electrical circuitsRadio waves are produced by oscillations in an electrical circuit.
  24. Atoms, nuclei and electromagnetic radiationElectromagnetic waves are produced by changes inside atoms and nuclei.

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