DC

• Direct Current
• We usually work in the range from 5 to 12 volts
• Let's measure some voltages

AC

• Alternating Current
• Typical Currents
• Household outlet: 110 volts
• Dryer, electric stove: 220 volts
• European household current: 220 volts
• A list of voltages from around the world
• Deadly!

Current

• The quantity of electrons passing through a given point
• Measured in Amperes (Amps for short)

Voltage

• The pressure for force with which the current moves
• Measured in Volts

Power

• The work perfomed by an electrical current
• Measured in Watts

Resistance

• The, well, resistance in a circuit to letting electricity pass through it
• Measured in Ohms ( Ω )

The Water Analogy

• Current = water
• Voltage = water pressure
• Power = erosion
• Resistance = the hose nozzel

Ohm's Law

• Ohm discovered that there is a direct proportionality between the voltage applied across a resistor and the resultant electrical current
• Voltage = Amperage (current) times Resistance
• V = A x R
• A = V / R
• R = V / A

A Schematic…

…is a conceptual diagram of the components and their connections in an electronic circuit

• Let's look at some…
• A useful link on reading and working with schematics