Voltage and Current

Voltage

Voltage is defined as the push, the pressure  received by the electrons at the source. Voltage sometimes is referred to as the electromotive force.

Voltage is measured in Volts.

The symbol for Voltage is V and the symbol for the unit of voltage (the volt) is also V.
The amount of voltage at the source (a battery or a cell, or  a generator) is determined by the Energy per unit Charge on the battery or cell, or generator.

The Volt is therefore defined as: one Joule of Energy per one Coulomb of Charge.

1 V = 1J/1C

or  V = E / Q

Where:   V is the voltage

              E is the energy of the electrons at the source
              Q is the charge of the electrons

Current

Current is the rate of flow of electrons in a circuit.  Electrons moving past a point in a circuit can be measured as the charge flow at that point in a circuit.  This means that if we measure the number of charges moving past a point in a circuit per unit time, we are actually measuring the current.

The symbol for current is I, and the symbol for current is A (Amperes or Amps for short).

according to the above definition, we can then write:

  Current = Charge / time
 

Using symbols....          

                                     I = Q / t

Where: I is the current, Q is the charge, and t is the time

The units will be ....Amperes - A (for current),  Coulombs - C (for charge), seconds - s (for time)