Use separate models for propagation/reflection and phase interference. Change the controls and compare the picture with the value at the selected probe.
Playback speed
Point sources (up to4)
Red, blue and gray encode signed displacement, not brightness or intensity. Fixed colour scales saturate; the probe reports the underlying computed value. A share URL saves controls, source configuration and probe, but not the current field or elapsed time. Paused controls still update the picture/readouts; reduced-motion preference initially pauses playback.
The finite-difference model uses a dimensionless180×120 grid. Grid spacing and integration step are1; c is cells/step, displayed time is step count/60 and f is cycles per displayed second. Temporal damping uses a centred difference. Fixed u=0 edges invert displacement on reflection; first-order Mur edges retain reflections at oblique incidence and corners. With zero damping, geometric spreading can still change local amplitudes.
The point model superposes waves in fixed700×500 reference coordinates, so viewport resizing does not change the wavelength meaning. At distance r it uses the far-field factor A exp(−αr/(3λ))/√r and omits r<1. α is the damping slider divided by100. It is not an exact near-field solution, a real double slit, a water tank or electromagnetic intensity.
How to use & worked examples
Use separate models for propagation/reflection and phase interference. Change the controls and compare the picture with the value at the selected probe.
In the grid model c=0.50 and f=0.80 give continuum reference λ=60c/f=37.5 cells. In the point model choose two opposite-phase sources with equal amplitudes and probe the centre: equal-distance contributions cancel, giving u≈0. Change one phase or amplitude and compare the centre value.
Model & applicability
The finite-difference model uses a dimensionless180×120 grid. Grid spacing and integration step are1; c is cells/step, displayed time is step count/60 and f is cycles per displayed second. Temporal damping uses a centred difference. Fixed u=0 edges invert displacement on reflection; first-order Mur edges retain reflections at oblique incidence and corners. With zero damping, geometric spreading can still change local amplitudes.
The point model superposes waves in fixed700×500 reference coordinates, so viewport resizing does not change the wavelength meaning. At distance r it uses the far-field factor A exp(−αr/(3λ))/√r and omits r<1. α is the damping slider divided by100. It is not an exact near-field solution, a real double slit, a water tank or electromagnetic intensity.
Red, blue and gray encode signed displacement, not brightness or intensity. Fixed colour scales saturate; the probe reports the underlying computed value. A share URL saves controls, source configuration and probe, but not the current field or elapsed time. Paused controls still update the picture/readouts; reduced-motion preference initially pauses playback.