Python/electronics/coulombs_law.py

87 lines
2.7 KiB
Python
Raw Normal View History

# 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 lélectricité et le magnétisme,"
Histoire de lAcadémie Royale des Sciences, pp. 569577.
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()