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ECE Formulas and Equations

The document provides a comprehensive list of electrical engineering formulas and equations related to Ohm's Law, resistors, capacitors, inductors, bipolar transistors, JFETs, MOSFETs, and reactance. It includes formulas for series and parallel configurations, as well as key relationships for capacitance, inductance, and digital logic states. Additionally, it highlights the phase relationships between voltage and current in inductors and capacitors.

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7 views2 pages

ECE Formulas and Equations

The document provides a comprehensive list of electrical engineering formulas and equations related to Ohm's Law, resistors, capacitors, inductors, bipolar transistors, JFETs, MOSFETs, and reactance. It includes formulas for series and parallel configurations, as well as key relationships for capacitance, inductance, and digital logic states. Additionally, it highlights the phase relationships between voltage and current in inductors and capacitors.

Uploaded by

ScribdTranslations
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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ECE Formulas and Equations

Name/Description Formula / Equation


V = IR; I = V/R; R = V/I where V and I are respectively the
Ohm's Law voltage across and current through a resistor with
resistance R;
P = VI = I2R = V2/Rwhere P is the power dissipated
Resistors in Resistors in Series: Reff = R1 + R2 + R3 + ... + RN
Series/Parallel Resistors in Parallel: 1/Reff = 1/R1 + 1/R2 + 1/R3 + ... +
1/RN

Capacitors in Capacitors in Series: 1/Ceff = 1/C1 + 1/C2 + 1/C3 + ... +


Series/Parallel 1/CN
Capacitors in Parallel:Ceff =C1 +C2 +C3 + ... +CN

Inductors in Inductors in Series: Leff = L1 + L2 + L3 + ... + LN


Series/Parallel Inductors in Parallel: 1/Leff = 1/L1 + 1/L2 + 1/L3 + ... +
1/LN
C = q/V; q = CV; V = q/C where V and q are respectively
the voltage across and charge in a capacitor with
Capacitance capacitanceC;
v = 1/C idt; i = C dv/dt where i is the current through
the capacitor and v is the voltage across the capacitor
i = 1/L vdt; v = L di/dt where i is the current through
Inductance
the inductor and v is the voltage across the inductor
hfe = ic / ib; hFE = Ic / Ib where hfe/hFE are the ac and
DC forward current transfer ratios, respectively, ic and Ic are the
ac and dc collector currents, ib and Ib are the ac and dc
base currents;
Bipolar Transistor Gm = ic / Vb where Gm is the mutual conductance, ic is
Formulas the ac signal collector-emitter current, and vbe is the
base-emitter voltage; note: voltage gain G = Gm x Rload
hie = hfe / Gm where hie is the input resistance, which
also equals the base input voltage divided by the base
current
Vp = Vpo + Vgs where Vgs is the gate-source voltage, Vp
the drain-source voltage that causes pinch off, Vpo is
the drain-source voltage at which saturation begins when
JFET Formulas Vgs = 0;
BVds = BVdso + Vgs where BVds is the breakdown
voltage and BVdso is the breakdown voltage when Vgs =
0
Vds = Vgs + Vth
Vds and Vsd are the drain-source and source-drain
MOSFET Formulas the voltages needed for pinch-off, respectively, Vgs and Vsg are the
gate-source and source-gate voltages, and Vth is the
MOSFET's threshold voltage

deMorgan's Theorem A·B = A + B; A + B = A · B where A and B are


digital logic states
X = 2πfL where X is the inductive reactance, L is the
inductance, and f is the frequency of the signal;
v = XIcos2πft where v is the voltage across an
Inductive Reactance inductance L if a sinusoidal current i = I sin 2πft is passed
through it, where I and f are the amplitude and frequency
of the current, respectively.
Note: In an inductance, current lags the voltage by 90 degrees.
deg.
Capacitive Reactance X = 1 / (2πfC) where X is the capacitive reactance, C is
the
capacitance, and f is the frequency of the signal;
i = Vcos(2πft)/X where i is the current through an
Capacitance C if a sinusoidal voltage v = V sin 2πft is
applied across it, where V and f are the amplitude and
frequency of the voltage, resp.
Note: In a capacitance, the voltage lags the current by 90.
deg.

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