diff --git a/DIRECTORY.md b/DIRECTORY.md
index d234d366d..44d0414a3 100644
--- a/DIRECTORY.md
+++ b/DIRECTORY.md
@@ -169,6 +169,7 @@
   * [Prefix Conversions](conversions/prefix_conversions.py)
   * [Prefix Conversions String](conversions/prefix_conversions_string.py)
   * [Pressure Conversions](conversions/pressure_conversions.py)
+  * [Rectangular To Polar](conversions/rectangular_to_polar.py)
   * [Rgb Cmyk Conversion](conversions/rgb_cmyk_conversion.py)
   * [Rgb Hsv Conversion](conversions/rgb_hsv_conversion.py)
   * [Roman Numerals](conversions/roman_numerals.py)
diff --git a/conversions/rectangular_to_polar.py b/conversions/rectangular_to_polar.py
new file mode 100644
index 000000000..bed97d741
--- /dev/null
+++ b/conversions/rectangular_to_polar.py
@@ -0,0 +1,32 @@
+import math
+
+
+def rectangular_to_polar(real: float, img: float) -> tuple[float, float]:
+    """
+    https://en.wikipedia.org/wiki/Polar_coordinate_system
+
+    >>> rectangular_to_polar(5,-5)
+    (7.07, -45.0)
+    >>> rectangular_to_polar(-1,1)
+    (1.41, 135.0)
+    >>> rectangular_to_polar(-1,-1)
+    (1.41, -135.0)
+    >>> rectangular_to_polar(1e-10,1e-10)
+    (0.0, 45.0)
+    >>> rectangular_to_polar(-1e-10,1e-10)
+    (0.0, 135.0)
+    >>> rectangular_to_polar(9.75,5.93)
+    (11.41, 31.31)
+    >>> rectangular_to_polar(10000,99999)
+    (100497.76, 84.29)
+    """
+
+    mod = round(math.sqrt((real**2) + (img**2)), 2)
+    ang = round(math.degrees(math.atan2(img, real)), 2)
+    return (mod, ang)
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()
diff --git a/electronics/electric_conductivity.py b/electronics/electric_conductivity.py
index 11f2a607d..65bb6c5ce 100644
--- a/electronics/electric_conductivity.py
+++ b/electronics/electric_conductivity.py
@@ -21,6 +21,26 @@ def electric_conductivity(
     ('conductivity', 5.12672e-14)
     >>> electric_conductivity(conductivity=1000, electron_conc=0, mobility=1200)
     ('electron_conc', 5.201506356240767e+18)
+    >>> electric_conductivity(conductivity=-10, electron_conc=100, mobility=0)
+    Traceback (most recent call last):
+        ...
+    ValueError: Conductivity cannot be negative
+    >>> electric_conductivity(conductivity=50, electron_conc=-10, mobility=0)
+    Traceback (most recent call last):
+        ...
+    ValueError: Electron concentration cannot be negative
+    >>> electric_conductivity(conductivity=50, electron_conc=0, mobility=-10)
+    Traceback (most recent call last):
+        ...
+    ValueError: mobility cannot be negative
+    >>> electric_conductivity(conductivity=50, electron_conc=0, mobility=0)
+    Traceback (most recent call last):
+        ...
+    ValueError: You cannot supply more or less than 2 values
+    >>> electric_conductivity(conductivity=50, electron_conc=200, mobility=300)
+    Traceback (most recent call last):
+        ...
+    ValueError: You cannot supply more or less than 2 values
     """
     if (conductivity, electron_conc, mobility).count(0) != 1:
         raise ValueError("You cannot supply more or less than 2 values")