Current Electricity

Electric Charge: a basic property of matter. It occurs in two states: positive + and negative - charge.
Current (I): the movement of charged particles from one place to another, measured in coulombs. It is the rate at which charge flows past a point in the circuit. Is measured in amps (A). An ammeter is used.
charge = total charge divided by time taken
Potential difference: the amount if energy potential in joules, lost by each coulomb of charge in a given part of a circuit.
PotDif = work divided by charge
Power: the rate of doing work, or the rate at which energy is transformed from one form to another. 
Resistance (W): is the ratio of potential difference across a component to the current flowing through it, it is measure in ohms.
Res = PotDif divided by current

 To convert the electrical energy into other forms of energy, loads resist the movement of charge.

One coulomb of charge is equal to 6.242 * 10^18 elementary charges. It is the measure of electric charge.
One elementary charge is equal to 1.602 * 10^-19 coulombs. 



An electric circuit is a closed loop of moving electric charge. 
A conductor is usually wires that connect elements in an electric circuit. 
A switch can stop or allow the current to flow.
A battery is multiple cells.


Direct Current (DC): refers to circuits where the net flow of charge is in one direction only. The current provided by the battery is direct current and usually flows at a steady rate.

 Alternating Current (AC): refers to circuits where charge carriers move back and forth periodically. Power points in your house are usually AC. 

 Resistors are used to control the current flowing through, and the voltage drop across, parts of a circuit.
Res = Voltage divided by current

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