Biot-savart-law

physics/Biot-savart-law.py

@@ -0,0 +1,67 @@
+"""
+Calculate the magnetic field (B) produced by a long straight current-carrying
+conductor at a distance r from the wire in free space.
+
+Equation for calculating magnetic field:
+B = (μ₀ * I) / (2 * π * r)
+
+where:
+B = Magnetic field (Tesla, T)
+μ₀ = Permeability of free space (4π × 10⁻⁷ T·m/A)
+I = Current (Amperes, A)
+r = Perpendicular distance from the wire (meters, m)
+
+https://en.wikipedia.org/wiki/Biot–Savart_law
+"""
+
+import math
+
+# Magnetic constant (Permeability of free space) in T·m/A
+mu_0 = 4 * math.pi * 1e-7
+
+
+def magnetic_field(current: float, distance: float, permeability: float = mu_0) -> float:
+    """
+    Args:
+        current: electric current through the wire (Amperes, A)
+        distance: perpendicular distance from the wire (meters, m)
+        permeability: permeability of the medium (T·m/A),
+            default is free space permeability (μ₀)
+
+    returns:
+        the magnetic field strength at the given point (Tesla, T)
+
+    >>> magnetic_field(current=10, distance=0.05)
+    3.9999999999999996e-05
+    >>> magnetic_field(current=5, distance=0.1)
+    1.0e-05
+    >>> magnetic_field(current=0, distance=0.1)
+    0.0
+    >>> magnetic_field(current=-5, distance=0.1)
+    Traceback (most recent call last):
+        ...
+    ValueError: Impossible current
+    >>> magnetic_field(current=5, distance=-0.1)
+    Traceback (most recent call last):
+        ...
+    ValueError: Impossible distance
+    >>> magnetic_field(current=5, distance=0)
+    Traceback (most recent call last):
+        ...
+    ZeroDivisionError: Distance cannot be zero
+    """
+
+    if current < 0:
+        raise ValueError("Impossible current")
+    if distance < 0:
+        raise ValueError("Impossible distance")
+    if distance == 0:
+        raise ZeroDivisionError("Distance cannot be zero")
+
+    return (permeability * current) / (2 * math.pi * distance)
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()