optics

Double Slit Interference

See Young's double slit experiment in 3D. Coherent light passes through two slits, producing an interference pattern on a distant screen. Adjust wavelength and slit separation to see fringe spacing change.

Double Slit

A-Level

When coherent light passes through two closely spaced slits, the overlapping waves interfere constructively (bright fringes) and destructively (dark fringes). The fringe spacing is proportional to wavelength and screen distance, inversely proportional to slit separation.

Wavelength550nm

Slit Separation0.5mm

Screen Distance4.0m

📐 Formulas

\Delta y = \frac{\lambda D}{d}Distance between adjacent bright fringes

d\sin\theta = n\lambdaPath difference = nλ for bright fringes

d\sin\theta = (n+\frac{1}{2})\lambdaPath difference = (n+½)λ for dark fringes

📋 Syllabus

AQA3.3.3.1

EdexcelTopic 5

OCR4.4.2