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Electricity and Electronics
Base of Modern Technology
Electricity
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Flow of electrons
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Originally conceived of as positive
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Now we know that they are negatively charged
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Flows from - to +
Properties of Electricity
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Voltage
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“Pressure” that moves electrons
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Also called EMF (Electromotive Force)
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Measured in Volts (V)
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Measured between two points
Properties of Electricity
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Current
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Quantity of electrons flowing past a certain point at
one time
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Measured in Amperes (A)
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Measured across one point
Properties of Electricity
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Resistance
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Opposition to flow of electrons
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Measured in Ohms (Ω)
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Measured across component(s)
Properties of Electricity
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Relationship of Voltage, Current and Resistance
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Ohm’s Law
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V = I*R
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1 volt can push 1 amp through 1 ohm
DC Current
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Electrons flow straight through from - to +
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Used in electronics and computers
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“Wall warts” (transformers) change from outlet AC to
DC
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AC (Alternating current) is sinusoidal
Sources
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Different types of sources
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Voltage source
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Battery
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Current source
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Ground
Resistors
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Resist flow of electrons
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Measured in Ohms with
an Ohmmeter
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Series and Parallel
Capacitors
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Capacitors resist
changes in current by
storing energy in an
electric field and
dissipating it
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Measured in farads
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Series and parallel
Transistors
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Used as amplifier
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Changes in Vin change
Vout
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3 pins
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Used by the billions in
electronics
555 Timer chip
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IC (Integrated Circuit)
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Large quantity
components in one
package
• http://ecee.colorado.edu/~mcleod/teaching/Ci
rcuits2250/Labs/lab01/index.html
• http://www.play-
hookey.com/dc_theory/fundamentals/
• http://en.wikipedia.org/wiki/Resistors
• http://en.wikipedia.org/wiki/Capacitor