Blog 1: Notes on Current Electricity

• An ELECTRIC CURRENT is a flow of microscopic particles called ELECTRONS flowing through a conductive material (usually a wire)

Simple electric current

• CURRENT: Total amount of charge moving past a point in a conductor divided by the time taken

      I = Q/t

where ... I = current in amperes (A)

                Q = charge in coulombs

                t  = time in seconds

@5:58: CURRENT explained.

• The direction that the current flows is from the negative terminal to the positive terminal

There are TWO types of electric currents:

• DIRECT CURRENT (DC) : current always flows in the same direction between the positive and negative terminals of a power supply to a load (device that uses energy)
• ALTERNATING CURRENT (AC) : the direction of the current reverses with the support of electric and magnetic forces
• Electric current is measured in amps (A) using an anmeter connected to the complete path of current called a circuit

If you could SEE the electric currents in a wire, they would look something like the following:

DIRECT CURRENT

ALTERNATING CURRENT

• ELECTRIC POTENTIAL DIFFERENCE (V): the electrical potential energy for each coulomb of charge in a circuit 

V= E/Q

where ... E = energy required to increase electric potential of a charge 
                Q = amount of charge
                V = the volt is the unit used to measure electric potential difference 



@6:30: Electric potential difference explained.

• ENERGY TRANSFER:

E = VIt

where ... E = energy in joules
              V = potential differencein volts
               I = current in amperes
              T = time in seconds  

• Voltmeter measures the potential difference between any two points, provided that it must be connect in parallel with the load in the circuit and had a large resistance so that its measurement will deflect a minimal current from the circuit