Interference Lantern Slide - Physics Demonstrations - Interference Lantern Slide | Physics Undergraduate Labs

Purpose

Visually demonstrates constructive and destructive interference using two overlapping wire sinusoids on a sliding mechanism. Moving the handle shifts one wave relative to the other, showing in-phase reinforcement and out-of-phase cancellation. Project on an overhead projector or document camera.

Wooden-framed box with glass panel containing two sinusoidal wire shapes, offset so peaks of one align with troughs of the other. Sliding handle visible on left.

Same wooden-framed box with the two sinusoidal wire patterns shifted so their peaks and troughs align in phase. Handle on left is in a different position.

Figure 1: Interference slide with the two wire sinusoids offset — peaks align with troughs, showing destructive interference.

Figure 2: Handle moved to align the wave patterns in phase — constructive interference, with combined amplitude appearing doubled.

Interference Lantern Slide

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