Updated 5-3-07

Things to Remember 1
OEES 135, OEET 210

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 Metric Prefixes

Name Abbreviation Meaning Number Power of 12
Pico p Trillionth 0.000,000,000,001 10-12
Nano n Billionth .000,000,001 10-9
Micro μ Millionth .000,001 10-6
Milli m Thousandth .001 10-3
Kilo k Thousand 1000 103
Mega M Million 1,000,000 106
Giga G Billion 1,000,000,000 109
Tera T Trillion 1,000,000,000,000 1012
 
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1
Math and Trig

sin θ = opposite/hypotenuse
cos θ = adjacent/hypotenuse
 tan θ = opposite/adjacent
 Pythagorean Theorem: c2 = a2 + b2 ,
where c = hypotenuse, and a and b are the other sides of the right triangle.
sin-1 (opposite/hypotenuse) =  θ
 cos-1 (adjacent/hypotenuse) = θ
tan-1 (opposite/adjacent) = θ		 The square root of x2 is x
sin-1 (sin θ ) = θ
cos-1 (cos θ ) = θ
 tan-1 (tan θ ) = θ
xa xb = xa+b
xa/xb = xa-b

AC

  • ELI the ICE man.
    • E means voltage (electromotive force).
    • L = inductance
    • I = current
    • C = capacitance
  • The voltage across an inductor leads the current through the inductor by 90 degrees.
  • The current through a capacitor leads the voltage across the capacitor by 90 degrees.
  • No power is used in an ideal inductor or an ideal capacitor.
  • The true power dissipated in a circuit containing resistors, inductors, and capacitors is equal to the power dissipated in the resistors.
  • True power is given by the formula P = IV * p.f.
  • Apparent power is given by the formula P = IV.
  • Thus, true power is apparent power times the power factor.
  • L = inductance
  • C = capacitance
  • XL = 2πfL
  • XC = 1/2πfC
  • P = IV * p.f.
  • p.f. = cos θ
  • X = reactance
  • Z = impedance
  • The unit for reactance and impedance is ohms.
  • High-frequency current has difficulty passing through an inductor.
  • Low-frequency current has difficulty passing through a capacitor.
  • A capacitor and an inductor can be used to create a resonant circuit . A resonant circuit can be used to either pass or block currents of a certain frequency, depending upon whether the two components are connected in series or in parallel.