Electricity and ElectronicsBase of Modern Technology

Electricity

• Flow of electrons• Originally conceived of as positive• Now we know that they are negatively charged• Flows from - to +

Properties of Electricity

• Voltage• “Pressure” that moves electrons• Also called EMF (Electromotive Force)• Measured in Volts (V)• Measured between two points

Properties of Electricity

• Current• Quantity of electrons flowing past a certain point at one time

• Measured in Amperes (A)• Measured across one point

Properties of Electricity

• Resistance• Opposition to flow of electrons• Measured in Ohms (Ω)• Measured across component(s)

Properties of Electricity

• Relationship of Voltage, Current and Resistance• Ohm’s Law• V = I*R• 1 volt can push 1 amp through 1 ohm

DC Current

• Electrons flow straight through from - to +• Used in electronics and computers• “Wall warts” (transformers) change from outlet AC to DC

• AC (Alternating current) is sinusoidal

Sources

• Different types of sources

• Voltage source• Battery• Current source• Ground

Resistors

• Resist flow of electrons

• Measured in Ohms with an Ohmmeter

• Series and Parallel

Capacitors

• Capacitors resist changes in current by storing energy in an electric field and dissipating it

• Measured in farads• Series and parallel

Transistors

• Used as amplifier• Changes in Vin change Vout

• 3 pins

• Used by the billions in electronics

555 Timer chip

• IC (Integrated Circuit)• Large quantity components in one package

•http://ecee.colorado.edu/~mcleod/teaching/Circuits2250/Labs/lab01/index.html

•http://www.play-hookey.com/dc_theory/fundamentals/

•http://en.wikipedia.org/wiki/Resistors

•http://en.wikipedia.org/wiki/Capacitor