diff --git a/DIRECTORY.md b/DIRECTORY.md
index 69bdb2b6c9d0..fcbe0ded03f6 100644
--- a/DIRECTORY.md
+++ b/DIRECTORY.md
@@ -479,6 +479,7 @@
   * [Ic 555 Timer](electronics/ic_555_timer.py)
   * [Ind Reactance](electronics/ind_reactance.py)
   * [Ohms Law](electronics/ohms_law.py)
+  * [Power Factor Correction](electronics/power_factor_correction.py)
   * [Real And Reactive Power](electronics/real_and_reactive_power.py)
   * [Resistor Color Code](electronics/resistor_color_code.py)
   * [Resistor Equivalence](electronics/resistor_equivalence.py)
@@ -876,6 +877,7 @@
   * [Test Factorial](maths/test_factorial.py)
   * [Test Prime Check](maths/test_prime_check.py)
   * [Three Sum](maths/three_sum.py)
+  * [Tonelli Shanks](maths/tonelli_shanks.py)
   * [Trailing Zeroes](maths/trailing_zeroes.py)
   * [Trapezoidal Rule](maths/trapezoidal_rule.py)
   * [Triplet Sum](maths/triplet_sum.py)
diff --git a/electronics/power_factor_correction.py b/electronics/power_factor_correction.py
new file mode 100644
index 000000000000..04affdb56d89
--- /dev/null
+++ b/electronics/power_factor_correction.py
@@ -0,0 +1,128 @@
+# https://www.electronics-tutorials.ws/accircuits/power-factor-correction.html
+# https://www.youtube.com/watch?v=YZcBkFdstEU
+
+import math
+
+
+def shunt_capacitor_power_factor_correction(
+    voltage: float,
+    frequency: float,
+    real_power: float,
+    current_power_factor: float,
+    expected_power_factor: float,
+) -> float:
+    """
+    Calculate shunt capacitor that will be added in order to achieve the
+    expected power factor
+
+    Examples:
+    >>> shunt_capacitor_power_factor_correction(120,60,4000,0.8,0.95)
+    0.00031043753362948597
+    >>> shunt_capacitor_power_factor_correction(150,50,2000,0.6,0.87)
+    0.00021690547192207782
+    >>> shunt_capacitor_power_factor_correction(115,0,800,0.6,0.87)
+    Traceback (most recent call last):
+      ...
+    ValueError: frequency is zero dc circuit
+    >>> shunt_capacitor_power_factor_correction(0,60,800,0.6,0.87)
+    Traceback (most recent call last):
+      ...
+    ValueError: voltage is zero no excitation
+    """
+
+    if (
+        not isinstance(current_power_factor, (int, float))
+        or not isinstance(expected_power_factor, (int, float))
+        or current_power_factor < -1
+        or current_power_factor > 1
+        or expected_power_factor < -1
+        or expected_power_factor > 1
+    ):
+        raise ValueError("power_factor must be a valid float value between -1 and 1.")
+
+    if frequency == 0:
+        raise ValueError("frequency is zero dc circuit")
+
+    if voltage == 0:
+        raise ValueError("voltage is zero no excitation")
+
+    current_theta = math.acos(current_power_factor)
+    expected_theta = math.acos(expected_power_factor)
+
+    current_apparent_power = real_power / current_power_factor
+    current_reactive_power = current_apparent_power * math.sin(current_theta)
+    expected_apparent_power = real_power / expected_power_factor
+    expected_reactive_power = expected_apparent_power * math.sin(expected_theta)
+
+    """
+    The difference between the new and old reactive powers is due to the
+    parallel addition of the capacitor to the load
+    """
+    change_reactive_power = current_reactive_power - expected_reactive_power
+
+    return change_reactive_power / (2 * math.pi * frequency * (voltage**2))
+
+
+def shunt_inductor_power_factor_correction(
+    voltage: float,
+    frequency: float,
+    real_power: float,
+    current_power_factor: float,
+    expected_power_factor: float,
+) -> float:
+    """
+    Calculate shunt capacitor that will be added in order to achieve the
+    expected power factor
+
+    Examples:
+    >>> shunt_inductor_power_factor_correction(120,60,4000,0.8,0.95)
+    0.02266540783980564
+    >>> shunt_inductor_power_factor_correction(120,60,4000,-0.8,-0.4)
+    0.006195660726930193
+    >>> shunt_inductor_power_factor_correction(115,0,800,-0.6,0.87)
+    Traceback (most recent call last):
+      ...
+    ValueError: frequency is zero dc circuit
+    >>> shunt_inductor_power_factor_correction(0,60,800,-0.6,0.87)
+    Traceback (most recent call last):
+      ...
+    ValueError: voltage is zero no excitation
+    """
+
+    if (
+        not isinstance(current_power_factor, (int, float))
+        or not isinstance(expected_power_factor, (int, float))
+        or current_power_factor < -1
+        or current_power_factor > 1
+        or expected_power_factor < -1
+        or expected_power_factor > 1
+    ):
+        raise ValueError("power_factor must be a valid float value between -1 and 1.")
+
+    if frequency == 0:
+        raise ValueError("frequency is zero dc circuit")
+
+    if voltage == 0:
+        raise ValueError("voltage is zero no excitation")
+
+    current_theta = math.acos(current_power_factor)
+    expected_theta = math.acos(expected_power_factor)
+
+    current_apparent_power = real_power / current_power_factor
+    current_reactive_power = current_apparent_power * math.sin(current_theta)
+    expected_apparent_power = real_power / expected_power_factor
+    expected_reactive_power = expected_apparent_power * math.sin(expected_theta)
+
+    """
+    The difference between the new and old reactive powers is due to the
+    parallel addition of the inductor to the load
+    """
+    change_reactive_power = current_reactive_power - expected_reactive_power
+
+    return (voltage**2) / (2 * math.pi * frequency * change_reactive_power)
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()