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Waves · Chapter 1: What is a wave?

Year 11 Science · About 14 minutes with activities · Turn your sound on

Chapter 1 · What is a wave?
Waves travel towards the shore →
The duck bobs up and downbut stays in the same place
Energy moves on, the water stays puta wave transfers energy, not matter
The wave (energy) travels →
Each fan stays in their own seat
Perpendicularat right angles to the wave
No overall displacementthe bead returns to the same spot
Examples: water waves, EM waves (light)
Rope wave: transverse, needs the ropeonly EM waves can cross a vacuum
Parallelback and forth along the wave direction
No crests or troughscompressions and rarefactions instead
No overall displacementthe red particle returns to the same spot
Example: sound
Space: a vacuumno particles
Silentno medium for sound
Light crosses the vacuumEM waves need no medium
3 × 10⁸ m/sfastest in a vacuum

Chapter 1 recap

  • A wave is a periodic disturbance of a medium or EM field. It transfers energy without transferring matter.
  • Transverse: oscillation perpendicular to the wave direction, crests and troughs. Longitudinal: oscillation parallel, compressions and rarefactions. Particles have no overall displacement.
  • EM waves need no medium and are fastest in a vacuum. Sound needs a medium and is faster in solids and liquids. Water and rope waves are transverse but need a medium.
  • Next: Chapter 2 · Measuring waves

A wave crosses the ocean, but the water stays put. How?

Chapter 1 · About 14 minutes · sound on

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