5-2-07

Reference Sheet for Some Quizzes
OEES 135, OEET 210

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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

  • 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.

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