diff --git a/Electronics/Physics_of_electricity/Current.md b/Electronics/Physics_of_electricity/Current.md
index 9b68d74..3f72ea7 100644
--- a/Electronics/Physics_of_electricity/Current.md
+++ b/Electronics/Physics_of_electricity/Current.md
@@ -6,10 +6,14 @@ tags: [physics, electricity]
 
 # Current
 
-When an appropriate external force is applied, the movement of electrons is from negatively charged atoms (negative ions) to positively charged atoms (positive ions). We call this electrical current. 
+When an appropriate external force is applied, the movement of electrons is from negatively charged atoms (negative ions) to positively charged atoms (positive ions). We call this **electrical current**. 
 
 We use the symbol $I$ to stand for current in equations. 
 
 > The amount of current is the sum of the charges of the moving electrons past a given point.
 
-We measure charge in Couloumbs.
\ No newline at end of file
+## Coulombs and amps
+
+We measure **charge** in Coulombs ($C$). A Coulomb is an aggregate of the charge of several electrons because their charge is so small: $6.24 \cdot 10 ^{18}$ electrons. 
+
+We measure **current** in amps. When one coulomb of charge moves past a point in one second it is called an **ampere** (amp) represented as $A$. 
diff --git a/Electronics/Physics_of_electricity/Electrons.md b/Electronics/Physics_of_electricity/Electrons.md
index 9b09bc4..eedfd73 100644
--- a/Electronics/Physics_of_electricity/Electrons.md
+++ b/Electronics/Physics_of_electricity/Electrons.md
@@ -22,7 +22,7 @@ The outer shell called the **valence shell** and the number of electrons it cont
 
 ## Conductivity and insularity 
 
-The conductivity of a material is an expression of its capacity to channel electrical charge. Where electrical charge is the flow of free electrons from one atom to another. The insularity of a material is the opposite: its capacity to resist the flow of electrical charge. 
+The **conductivity** of a material is an expression of its capacity to channel electrical charge. Where electrical charge is the _flow of free electrons from one atom to another_. The **insularity** of a material is the opposite: its _capacity to resist the flow of electrical charge_. 
 
 Electrons in the valence shell can gain energy from external forces. If these electrons gain  enough energy, they can leave the atom and become **free electrons**, moving randomly from atom to atom.
 
@@ -39,4 +39,4 @@ When an atom has an equal number of protons and electrons it is said to be **ele
 
 A balanced atom that receives one or more extra electrons gives way to an overall negative charge. An atom in this state is a **negative ion**. Conversely if a balanced atom loses one or more electrons it becomes positively charged and is thus called a **positive ion**. 
 
-> The process of ionization is constitutive of the flow of current.
+> The process of ionization is a constitutive part of the flow of current but not the only part. We also must factor the force that triggers ionization and the resistance that impedes it. 
diff --git a/Electronics/Physics_of_electricity/Voltage.md b/Electronics/Physics_of_electricity/Voltage.md
new file mode 100644
index 0000000..7e90e51
--- /dev/null
+++ b/Electronics/Physics_of_electricity/Voltage.md
@@ -0,0 +1,7 @@
+---
+categories:
+  - Electronics
+tags: [physics, electricity]
+---
+
+# Voltage