diff --git a/source/electronics/components.rst b/source/electronics/components.rst
index 23c8edc..fdeed9b 100644
--- a/source/electronics/components.rst
+++ b/source/electronics/components.rst
@@ -2,8 +2,8 @@ Components
 ---------------
 
 Two types of electronic components:
-	1) Active: Source of energy (includes amplifying components such as transistors)
-	2) Passive: Cannot introduce energy into the circuit
+	1) Active: Source of energy (includes amplifying components such as transistors).
+	2) Passive: Cannot introduce energy into the circuit.
 
 .. note::
 	You can design svg circuits using the `Electrical Symbols Library <https://upload.wikimedia.org/wikipedia/commons/6/6a/Electrical_symbols_library.svg>`__:
@@ -18,5 +18,5 @@ Generators
 .. include:: esl.rst
 
 There are two important generators to know:
-	1) Current generators |igen_c|
-	2) Voltage generators |igen_v|
+	1) Current generators |igen_c| that strive to maintain constant current on his terminals. Arrow must point towards the current direction (`source <https://ultimateelectronicsbook.com/labeling-voltages-currents-nodes/>`__).
+	2) Voltage generators |igen_v| that strive to maintain constant voltage on his terminals.
diff --git a/source/electronics/metrics.rst b/source/electronics/metrics.rst
new file mode 100644
index 0000000..ae66281
--- /dev/null
+++ b/source/electronics/metrics.rst
@@ -0,0 +1,21 @@
+Metrics
+---------------
+
+
+Coulomb
+^^^^^^^^^^
+
+In a circuit, charges (electrons) flow.
+This amount of charge is extremely huge.
+The *Coulomb* unit allows to count them more easily.
+Thus, :math:`1C \approx 6.241e^{18}` charges (electrons in our case).
+
+Newton
+^^^^^^^^^^^
+It is a unit of force.
+It is indirectly used in electronics (see Joule).
+One Newton is the force required to accelerate :math:`1Kg` of mass, at a rate of
+:math:`1m.s^{-1}` every seconds. 
+
+.. math::
+	[N]=kg.m.s^{-2}
diff --git a/source/index.rst b/source/index.rst
index fba6826..f23e9ca 100644
--- a/source/index.rst
+++ b/source/index.rst
@@ -33,6 +33,7 @@ Welcome to ScienceNotes's documentation!
    :numbered:
    :caption: Electronics
 
+   electronics/metrics.rst
    electronics/components.rst
 
 Indices and tables