Electrical law and theorems
Electrical law and theorems
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Named after: Georg Ohm
Ohm's law says voltage across a conductor is proportional to current flowing in, with all physical conditions/temperatures constant.
Resistance = R
Unit measure: Ohms (Ω)
R = P/I²
R = E/I
R = V²/P
Voltage = V or E
Measuring unit: Volts (V)
V = I*R
V = P/I
V = √(P/I)
Power = P
Measuring unit: Watts (W)
P = IE
P = I²*R
P = E²/R
Kirchhoff’s circuit laws (KCL) are 2 laws/equalities of current and potential difference (voltage) in circuits.
Kirchhoff’s current law (also KCL) says any circuit's node/junction has same current value flowing in and flowing out.
Kirchhoff’s voltage law (KVL) says the directed voltages sum around any closed loop is 0.
KCL: ∑ Iin = VIout
KVL: ∑V = 0
Named after: Gustav Robert Kirchhoff
Voltage and current divider formula
Voltage and current divider formula
The voltage divider formula is an extension to Ohm's Law and KVL. It's also used to calculate potentiometer values.
KVL formula: Vout = Vin * (R2 / (R1 + R2))
The current divider formula is
CDF formula:
Transformers' voltage, current, and turn ratio formula:
Reflected impedance formula: Zp = a² Zs = (Np/Ns)²*Rl
Zp = impedance "seen" by the primary
Zs = Rl = load impedance connected to the secondary (maybe resistive/inductive/capacitive).
a = (Np/Ns)² = turns ratio (primary:secondary)
Peak voltage (Pk) formula: Vrms*√2
Peak-to-peak voltage formula: 2*pk = 2*Vrms*√2
Power conservation formula: VpIp = VsIs
The superposition theorem says all branches' total VT or IT equal independent voltage sources, with other sources off/deactivated--voltage sources are replaced by short circuits, current sources by open circuits.
Thevenin’s theorem
Thevenin’s theorem
Thevenin’s theorem says
Vth = Thevenin voltage
Rth = Thevenin resistance
Named after: Léon Charles Thévenin
Norton’s theorem
Norton’s theorem
Max power transfer theorem
Max power transfer theorem
Millman’s theorem
Millman’s theorem
Tellegen’s theorem
Tellegen’s theorem
Reciprocity theorem
Reciprocity theorem
Substitution theorem
Substitution theorem
Compensated theorem
Compensated theorem
References
References
Quizzes
Quizzes
[Q1] Flashcards
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