Python/electronics/wheatstone_bridge.py at master · TheAlgorithms/Python · GitHub

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# ruff: noqa: RUF002 -- ambiguous-unicode-character-docstring
from __future__ import annotations


def wheatstone_solver(
    resistance_1: float, resistance_2: float, resistance_3: float
) -> float:
    r"""
    Calculate the unknown resistance (Rx) in a Wheatstone bridge circuit.

    Wheatstone Bridge is an electrical circuit used to accurately measure
    an unknown resistance by balancing two legs of a bridge circuit.

    This function calculates Rx when the three other resistances in the
    bridge are known. The bridge is said to be balanced when no current
    flows through the galvanometer connected between the midpoints of the
    two voltage dividers.
    * # https://en.wikipedia.org/wiki/Wheatstone_bridge

    Circuit Diagram:

         R1         R2
      +--/\/\/--+--/\/\/--+
      |         |         |
     Vin       Vg        Vout
      |         |         |
      +--/\/\/--+--/\/\/--+
         R3        Rx

    Balance condition:
      R1 / R2 = R3 / R4

    This solver uses the balanced bridge formula:
    Rx = (R2/R1) × R3

    Args:
        resistance_1 (R1): First known resistance
        resistance_2 (R2): Second known resistance
        resistance_3 (R3): Third known resistance

    Returns:
        float: The calculated unknown resistance (Rx)

      Applications:
      - Measurement of unknown resistance
      - Strain gauge circuits
      - Sensor calibration

    Usage examples:
    >>> wheatstone_solver(resistance_1=2, resistance_2=4, resistance_3=5)
    10.0
    >>> wheatstone_solver(resistance_1=356, resistance_2=234, resistance_3=976)
    641.5280898876405
    >>> wheatstone_solver(resistance_1=2, resistance_2=-1, resistance_3=2)
    Traceback (most recent call last):
        ...
    ValueError: All resistance values must be positive
    >>> wheatstone_solver(resistance_1=0, resistance_2=0, resistance_3=2)
    Traceback (most recent call last):
        ...
    ValueError: All resistance values must be positive
    """

    if resistance_1 <= 0 or resistance_2 <= 0 or resistance_3 <= 0:
        raise ValueError("All resistance values must be positive")
    return float((resistance_2 / resistance_1) * resistance_3)


if __name__ == "__main__":
    import doctest

    doctest.testmod()