diff --git a/electronics/resistor_equivalence.py b/electronics/resistor_equivalence.py
new file mode 100644
index 000000000..7142f838a
--- /dev/null
+++ b/electronics/resistor_equivalence.py
@@ -0,0 +1,58 @@
+# https://byjus.com/equivalent-resistance-formula/
+
+from __future__ import annotations
+
+
+def resistor_parallel(resistors: list[float]) -> float:
+    """
+    Req = 1/ (1/R1 + 1/R2 + ... + 1/Rn)
+
+    >>> resistor_parallel([3.21389, 2, 3])
+    0.8737571620498019
+    >>> resistor_parallel([3.21389, 2, -3])
+    Traceback (most recent call last):
+        ...
+    ValueError: Resistor at index 2 has a negative or zero value!
+    >>> resistor_parallel([3.21389, 2, 0.000])
+    Traceback (most recent call last):
+        ...
+    ValueError: Resistor at index 2 has a negative or zero value!
+    """
+
+    first_sum = 0.00
+    index = 0
+    for resistor in resistors:
+        if resistor <= 0:
+            raise ValueError(f"Resistor at index {index} has a negative or zero value!")
+        first_sum += 1 / float(resistor)
+        index += 1
+    return 1 / first_sum
+
+
+def resistor_series(resistors: list[float]) -> float:
+    """
+    Req = R1 + R2 + ... + Rn
+
+    Calculate the equivalent resistance for any number of resistors in parallel.
+
+    >>> resistor_series([3.21389, 2, 3])
+    8.21389
+    >>> resistor_series([3.21389, 2, -3])
+    Traceback (most recent call last):
+        ...
+    ValueError: Resistor at index 2 has a negative value!
+    """
+    sum_r = 0.00
+    index = 0
+    for resistor in resistors:
+        sum_r += resistor
+        if resistor < 0:
+            raise ValueError(f"Resistor at index {index} has a negative value!")
+        index += 1
+    return sum_r
+
+
+if __name__ == "__main__":
+    import doctest
+
+    doctest.testmod()