Electricity
I. What is electric current?
The flow of charges/electrical energy through a solid material (metals)
II. Circuits
A. Components – wires, switches, motors that are connected to provide a path through which electricity travels.
B. Switches – turn circuits on and off
C. Circuit diagram (schematic)
1. Wire – straight line
2. Battery 
3. Resistor 
4.
Switch 
D. Resistors – any electrical component that uses energy.
E. Open circuit – When a switch is in the off position; breaks prevent current
F. Closed circuit – When a switch is in on position; current flows
III. Charges
A. Kinds – positive and negative
B. Electrostatic forces – forces between positive and negative charges; because most objects are neutral, they hold many objects together.
C. Protons and Electrons – electrons stay within the atom because they are attracted to the protons in the nucleus.
IV. Voltage
A. Battery – is chemical energy used to move charge particles through a wire
B. Volts – measure the energy level at a certain place in a circuit.
1. A 1.5 volt battery – adds 1.5 joules of energy that leaves the positive end of a battery.
2. When a battery dies – there is not enough energy to push the charges through the circuit.
C. Measuring Voltage – negative terminal assigned 0 V, all other places on the circuit relative to this value. All points on a wire are the same voltage.
D. Usage – When energy (chemical from battery) is used, voltage drops
V. Current – is a flow of electric charges.
A. Flow – from high voltage to low voltage (plus to minus)
B. Charges – already present in the wire; battery repels electrons in the wire, which
repel other electrons in the wire, etc.
C. Voltage vs. Current – voltage supplies energy to make charges flow; current carries energy.
D. Ampere – unit for the measurement of current
E. Circuit breaker – prevents the current from becoming damaged if too much current is received.
F. Alternating current – direction of current in the circuit goes back and forth (as in your home).
G. Direct current – battery only makes current flow in one direction.
VI. Resistance
A. conductor – allows current to pass through it easily
B. insulator – prevents the passage of electric current
C. Resistance – a measure of how easily charges flow through an object.
1. Units – ohm (W) is the unit of resistance
2. Ohm’s Law – the current in a circuit is directly proportional to the voltage and inversely proportional to the resistance.
3. Current = Voltage/Resistance or I = V/R