gen-define-constructive-and-destructive-interference-and-give-on-0ebc

Define constructive and destructive interference and give one short worked example.

# Interference ## Definitions **Constructive Interference:** Occurs when two or more waves meet in phase (crests align with crests), causing their amplitudes to add together, producing a wave of greater amplitude. **Destructive Interference:** Occurs when two or more waves meet out of phase (crests align with troughs), causing their amplitudes to cancel each other, producing a wave of reduced or zero amplitude. ## Worked Example Two sound waves from separate speakers arrive at a point: - Wave 1: amplitude = 3 units - Wave 2: amplitude = 3 units **Constructive interference** (waves in phase): - Resultant amplitude = 3 + 3 = **6 units** - The sound is louder **Destructive interference** (waves exactly out of phase): - Resultant amplitude = 3 + (−3) = **0 units** - No sound is heard (complete cancellation) **Partial destructive interference** (waves partially out of phase): - If phase difference is 90°, resultant amplitude ≈ **4.2 units** - The sound is quieter than constructive but not completely cancelled This principle explains why you hear loud and soft spots when walking past two speakers playing the same tone.