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Waves · Chapter 3: The electromagnetic spectrum

Year 11 Science · About 15 minutes with activities · Turn your sound on

Chapter 3 · EM spectrum
All electromagnetic wavessame family · different wavelengths
Empty space: a vacuumno particles, no medium needed
3 × 10⁸ m/sthe speed of light in a vacuum
Frequency gets higher →photon energy gets higher too
Wavelength gets shorter →radio: up to kilometres · gamma: smaller than an atom
Can damage living cellsultraviolet · X-rays · gamma rays

Chapter 3 recap

  • EM waves are transverse, need no medium and travel at 3 × 10⁸ m/s in a vacuum.
  • Longest → shortest wavelength (lowest → highest frequency): radio, microwaves, infrared, visible, ultraviolet, X-rays, gamma. Raging Martians Invaded Venus Using X-ray Guns.
  • Uses: communications (radio, microwaves, infrared fibres), photos (visible), security ink (UV), bones (X-rays), sterilising (gamma). A photon is a packet of energy: higher frequency, more energy.
  • Next: Chapter 4 · Reflection and echoes

Your phone, your microwave and an X-ray machine use the same kind of wave. How?

Chapter 3 · About 15 minutes · sound on

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