← all cardsTopic 8 · Oscillations · Definitions
Phase difference, φ
The fraction of a cycle by which one oscillation leads or lags another, expressed as an angle (2π rad = one full cycle).
What this actually means
How far one oscillation is ahead of or behind another, as a fraction of a cycle in angle form. There is no λ here; the working fraction is Δt/T.
0 means in phase, π means antiphase. Quote answers within 0 to 2π.
Phase difference between two oscillations only holds meaning when they share a frequency; otherwise it drifts continuously.
Prove it — watch it be true
- Watch the x and v phasors rotate together
- The angle between them never changes: a fixed phase difference
- Read it off: a quarter turn, π/2