Two-source interference
Two-source interference is an interactive experiment in Oscillations & Waves, a free simulation from StudyFi Lab that runs right in your browser.
Two sources vibrating in phase send out waves of the same wavelength λ. Where the path difference Δr = |r₁ − r₂| is a whole number of wavelengths, the waves add up (bright fringe); where Δr is an odd multiple of λ/2, they cancel (dark fringe). The colour shows the intensity I = cos²(πΔr/λ).
Try this: Move the sources further apart and watch the number of fringes grow. Then drag point P onto a dark fringe and read Δr/λ.
Frequently asked questions
What does the “Two-source interference” experiment show?
Two sources vibrating in phase send out waves of the same wavelength λ. Where the path difference Δr = |r₁ − r₂| is a whole number of wavelengths, the waves add up (bright fringe); where Δr is an odd multiple of λ/2, they cancel (dark fringe). The colour shows the intensity I = cos²(πΔr/λ).
How do I try “Two-source interference”?
Move the sources further apart and watch the number of fringes grow. Then drag point P onto a dark fringe and read Δr/λ.
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