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1 files changed, 22 insertions, 0 deletions

diff --git a/src/physics/electricField.ts b/src/physics/electricField.ts
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+++ b/src/physics/electricField.ts
@@ -0,0 +1,22 @@
+export interface Point { x: number; y: number; z: number }
+export interface Charge extends Point { coulombs: number }
+export const COULOMB_CONSTANT = 8.9875517923e9;
+
+/** SI units: positions in metres, charges in coulombs, output in N/C.
+ * Samples inside 0.18 m of a charge are omitted to avoid visual singularities.
+ */
+export function electricField(point: Point, charges: readonly Charge[]): Point {
+  const field = { x: 0, y: 0, z: 0 };
+  for (const charge of charges) {
+    const dx = point.x - charge.x;
+    const dy = point.y - charge.y;
+    const dz = point.z - charge.z;
+    const r2 = dx * dx + dy * dy + dz * dz;
+    if (r2 < 0.18 ** 2) continue;
+    const factor = COULOMB_CONSTANT * charge.coulombs / (r2 * Math.sqrt(r2));
+    field.x += factor * dx;
+    field.y += factor * dy;
+    field.z += factor * dz;
+  }
+  return field;
+}