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Double-Slit Experiment
Wave Interference & Quantum Superposition Lab
48 px
Short (20)Long (100)
80 px
Narrow (30)Wide (180)
≋ Wave Mode — Observe continuous interference fringes. Adjust λ and d to shift the pattern in real time.
Constructive Interference Condition
d·sin(θ) = m·λ
Slit Separation (d)
80 px
Wavelength (λ)
48 px
Ratio d/λ
1.67
1st-order angle θ₁
36.9°
Bright Fringe Positions
| Order (m) | Path Diff Δ | Angle θ |
|---|---|---|
| m = -1 | 48 px | -36.9° |
| m = 0 | 0 px | 0.0° |
| m = 1 | 48 px | 36.9° |
Wave Explanation
Each slit acts as a new point source (Huygens' Principle). The two expanding wavefronts overlap — where crest meets crest, constructive interference creates a bright fringe. Where crest meets trough, destructive interference produces a dark zone.
Increasing λ or decreasing d spreads the fringes wider. The ratio d/λ controls fringe spacing.