Add implementation of Coulomb's Law

electronics/coulombs_law.py

@@ -0,0 +1,86 @@
+# https://en.wikipedia.org/wiki/Coulomb%27s_law
+
+from __future__ import annotations
+
+COULOMBS_CONSTANT = 8.988e9  # units = N * m^s * C^-2
+
+
+def couloumbs_law(
+    force: float, charge1: float, charge2: float, distance: float
+) -> dict[str, float]:
+
+    """
+    Apply Coulomb's Law on any three given values. These can be force, charge1,
+    charge2, or distance, and then in a Python dict return name/value pair of
+    the zero value.
+
+    Coulomb's Law states that the magnitude of the electrostatic force of
+    attraction or repulsion between two point charges is directly proportional
+    to the product of the magnitudes of charges and inversely proportional to
+    the square of the distance between them.
+
+    Reference
+    ----------
+    Coulomb (1785) "Premier mémoire sur l’électricité et le magnétisme,"
+    Histoire de l’Académie Royale des Sciences, pp. 569–577.
+
+    Parameters
+    ----------
+    force : float with units in Newtons
+
+    charge1 : float with units in Coulombs
+
+    charge2 : float with units in Coulombs
+
+    distance : float with units in meters
+
+    Returns
+    -------
+    result : dict name/value pair of the zero value
+
+    >>> couloumbs_law(force=0, charge1=3, charge2=5, distance=2000)
+    {'force': 33705.0}
+
+    >>> couloumbs_law(force=10, charge1=3, charge2=5, distance=0)
+    {'distance': 116112.01488218177}
+
+    >>> couloumbs_law(force=10, charge1=0, charge2=5, distance=2000)
+    {'charge1': 0.0008900756564307966}
+
+    >>> couloumbs_law(force=0, charge1=0, charge2=5, distance=2000)
+    Traceback (most recent call last):
+      ...
+    ValueError: One and only one argument must be 0
+
+    >>> couloumbs_law(force=0, charge1=3, charge2=5, distance=-2000)
+    Traceback (most recent call last):
+      ...
+    ValueError: Distance cannot be negative
+
+    """
+
+    charge_product = abs(charge1 * charge2)
+
+    if (force, charge1, charge2, distance).count(0) != 1:
+        raise ValueError("One and only one argument must be 0")
+    if distance < 0:
+        raise ValueError("Distance cannot be negative")
+    if force == 0:
+        force = COULOMBS_CONSTANT * charge_product / (distance ** 2)
+        return {"force": force}
+    elif charge1 == 0:
+        charge1 = abs(force) * (distance ** 2) / (COULOMBS_CONSTANT * charge2)
+        return {"charge1": charge1}
+    elif charge2 == 0:
+        charge2 = abs(force) * (distance ** 2) / (COULOMBS_CONSTANT * charge1)
+        return {"charge2": charge2}
+    elif distance == 0:
+        distance = (COULOMBS_CONSTANT * charge_product / abs(force)) ** 0.5
+        return {"distance": distance}
+    raise ValueError("Exactly one argument must be 0")
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()