Skip to content
Dabour HubLEARN · PRACTICE · EXPLORESign inStudent

4.9.8Electrons, Waves and Photons

Stationary vs Progressive Waves

5 min read 4 parts Lesson 61 of 62 Unit quiz Virtual lab

0%read

Part 1 of 4Progressive Waves

4.9.8 Stationary vs Progressive Waves
Energy
  • A progressive wave transfers energy from one place to another in the direction of travel.
Amplitude
  • Every point along the wave reaches the same maximum amplitude, assuming no energy is lost.
Phase
  • Points within one wavelength are all at different phases, and the phase changes steadily along the wave.
Profile
  • The wave profile moves through the medium at the wave speed.

Part 2 of 4Stationary Waves

Stationary Waves
Energy
  • No net energy is transferred along the medium, because the energy is trapped between the nodes.
Amplitude
  • Amplitude varies from zero at a node to a maximum at an antinode.
Phase
  • All points between two adjacent nodes oscillate in phase, and points in the next loop are in antiphase.
Wavelength
  • The wavelength is twice the distance between neighbouring nodes.

Part 3 of 4Direct Comparison

Direct Comparison
Frequency
  • Each point on a stationary wave still oscillates at the same frequency as the original waves.
Pattern
  • The pattern of nodes and antinodes does not move, unlike the profile of a progressive wave.
Formation
  • A progressive wave needs only a source, whereas a stationary wave needs two waves travelling in opposite directions.
FeatureProgressive waveStationary wave
Energy transferYes, along the waveNo net transfer
AmplitudeSame at all pointsZero at nodes, maximum at antinodes
PhaseChanges along the waveSame within a loop, opposite in neighbouring loops
ProfileMoves forwardFixed in position

Part 4 of 4Exam Checklist & Tips

4.9.8 – Key Points for the Exam

  • Node A point on a stationary wave where the amplitude is always zero.
  • Antinode A point on a stationary wave where the amplitude is a maximum.
  • Progressive wave A wave that transfers energy from a source to another place.
  • Phase A measure of the position of a point within its oscillation cycle.

Common Mistakes

  • Saying that all points on a stationary wave have the same amplitude; only points in the same position do.
  • Claiming that all points on a stationary wave are in phase; neighbouring loops are in antiphase.
  • Stating that stationary waves transfer no energy at all; the correct phrase is no net energy transfer.
  • Mixing up node spacing with wavelength; adjacent nodes are λ/2 apart.
Try it in the virtual labWaves \n