Narrow Slit, Wide Pattern

You'll learnwhy a wave spreads more through a narrower opening, why the wavelength compared with the opening is what decides it, and which fringes the single-slit equation locates.

Narrow the opening and the wave fans out wider, and the same doorway floods a room with sound while casting a sharp shadow in light. Ten short steps; press Next for each one.

10 STEPS · 6 QUICK CHECKS · NARROWER SPREADS WIDER · COMPARE λ WITH a · v2

narrower opening, wider pattern · compare λ with a, never a alone

Before you start

What you're looking at

Plane wavefronts meeting a barrier with one opening, and the arcs that spread beyond it. The opening narrows and widens during the animation.

The question

Does a narrower gap spread the wave more, or less, and what decides it?

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