Skip to content
Weave templates

Physics — Two-Source Interference (Young's Double Slit)

Young's double slit with a 633 nm laser, d = 0.25 mm and L = 2.00 m: path difference, the maxima and minima conditions, and a fringe spacing of 5.06 mm worked out.

Template previewWeave
Rendering…

Make it your own.

{
  "nodes": [
    {
      "id": "wi-screen",
      "type": "container",
      "label": "Screen at L = 2.00 m from the slits",
      "x": 1160,
      "y": 10,
      "width": 560,
      "height": 1050,
      "fill": "rgba(241,245,249,0.55)",
      "stroke": "#94a3b8"
    },
    {
      "id": "wi-approx",
      "type": "note",
      "label": "Path difference Δ = d sinθ, and for y ≪ L the small-angle form Δ ≈ dy/L is good to better than 0.1 %. Here θ is only 0.15° at the first maximum.",
      "x": 60,
      "y": 235,
      "width": 240,
      "height": 117,
      "fill": "#fef9c3",
      "stroke": "#ca8a04"
    },
    {
      "id": "wi-m2u",
      "type": "stadium",
      "label": "m = +2  ·  Δ = 2λ  ·  y = +10.13 mm",
      "x": 1180,
      "y": 235,
      "width": 240,
      "height": 117,
      "fill": "#dcfce7",
      "stroke": "#15803d"
    },
    {
      "id": "wi-s1",
      "type": "rect",
      "label": "Slit S₁ — coherent secondary source",
      "x": 620,
      "y": 410,
      "width": 240,
      "height": 117,
      "fill": "#ede9fe",
      "stroke": "#6d28d9"
    },
    {
      "id": "wi-m1u",
      "type": "stadium",
      "label": "m = +1  ·  Δ = λ  ·  y = +5.06 mm",
      "x": 1180,
      "y": 410,
      "width": 240,
      "height": 117,
      "fill": "#dcfce7",
      "stroke": "#15803d"
    },
    {
      "id": "wi-laser",
      "type": "rounded",
      "label": "He–Ne laser  ·  λ = 633 nm, monochromatic",
      "x": 60,
      "y": 585,
      "width": 240,
      "height": 117,
      "fill": "#e0f2fe",
      "stroke": "#0369a1"
    },
    {
      "id": "wi-slit0",
      "type": "rect",
      "label": "Single slit — makes the wavefront spatially coherent",
      "x": 340,
      "y": 585,
      "width": 240,
      "height": 117,
      "fill": "#fef3c7",
      "stroke": "#b45309"
    },
    {
      "id": "wi-m0",
      "type": "stadium",
      "label": "m = 0  ·  Δ = 0  ·  central maximum, y = 0",
      "x": 1180,
      "y": 585,
      "width": 240,
      "height": 117,
      "fill": "#fce7f3",
      "stroke": "#be185d"
    },
    {
      "id": "wi-s2",
      "type": "rect",
      "label": "Slit S₂ — separation d = 0.25 mm",
      "x": 620,
      "y": 760,
      "width": 240,
      "height": 117,
      "fill": "#ede9fe",
      "stroke": "#6d28d9"
    },
    {
      "id": "wi-m1d",
      "type": "stadium",
      "label": "m = −1  ·  Δ = λ  ·  y = −5.06 mm",
      "x": 1180,
      "y": 760,
      "width": 240,
      "height": 117,
      "fill": "#dcfce7",
      "stroke": "#15803d"
    },
    {
      "id": "wi-m2d",
      "type": "stadium",
      "label": "m = −2  ·  Δ = 2λ  ·  y = −10.13 mm",
      "x": 1180,
      "y": 935,
      "width": 240,
      "height": 117,
      "fill": "#dcfce7",
      "stroke": "#15803d"
    },
    {
      "id": "wi-spacing",
      "type": "note",
      "label": "Fringe spacing y = λL/d = (633 × 10⁻⁹ × 2.00) ÷ (0.25 × 10⁻³) = 5.06 mm. Widen the slits' separation and the fringes crowd together.",
      "x": 60,
      "y": 1110,
      "width": 520,
      "height": 117,
      "fill": "#fef9c3",
      "stroke": "#ca8a04"
    },
    {
      "id": "wi-conditions",
      "type": "note",
      "label": "Maxima where d sinθ = mλ (waves arrive in phase); minima where d sinθ = (m + ½)λ (exactly out of phase). Superposition does the rest.",
      "x": 620,
      "y": 1110,
      "width": 520,
      "height": 117,
      "fill": "#fef9c3",
      "stroke": "#ca8a04"
    },
    {
      "id": "wi-minima",
      "type": "note",
      "label": "Dark fringes fall between the bright ones, at y = ±2.53 mm and ±7.59 mm. Energy is redistributed, not destroyed — the total across the screen is unchanged.",
      "x": 1180,
      "y": 1110,
      "width": 520,
      "height": 117,
      "fill": "#fef9c3",
      "stroke": "#ca8a04"
    }
  ],
  "edges": [
    {
      "id": "wi-e1",
      "source": "wi-laser",
      "target": "wi-slit0"
    },
    {
      "id": "wi-e2",
      "source": "wi-slit0",
      "target": "wi-s1",
      "label": "wavefront reaches both slits together"
    },
    {
      "id": "wi-e3",
      "source": "wi-slit0",
      "target": "wi-s2"
    },
    {
      "id": "wi-e4",
      "source": "wi-s1",
      "target": "wi-m2u"
    },
    {
      "id": "wi-e5",
      "source": "wi-s1",
      "target": "wi-m1u"
    },
    {
      "id": "wi-e6",
      "source": "wi-s1",
      "target": "wi-m0"
    },
    {
      "id": "wi-e7",
      "source": "wi-s1",
      "target": "wi-m1d"
    },
    {
      "id": "wi-e8",
      "source": "wi-s1",
      "target": "wi-m2d"
    },
    {
      "id": "wi-e9",
      "source": "wi-s2",
      "target": "wi-m2u"
    },
    {
      "id": "wi-e10",
      "source": "wi-s2",
      "target": "wi-m1u"
    },
    {
      "id": "wi-e11",
      "source": "wi-s2",
      "target": "wi-m0",
      "label": "equal path lengths"
    },
    {
      "id": "wi-e12",
      "source": "wi-s2",
      "target": "wi-m1d"
    },
    {
      "id": "wi-e13",
      "source": "wi-s2",
      "target": "wi-m2d"
    }
  ]
}