Direct Current (DC) Electricity
Fundamental Laws
Ohm’s Law
where:
= voltage (V) = current (A) = resistance (Ω)
Series and Parallel Resistances
Series Resistances
Parallel Resistances
Power in DC Circuits
Electrical Power
- Using Ohm’s law, it can also be expressed as:
Alternating Current (AC) Electricity
Single-Phase Circuits
Root Mean Square (RMS)
Total Impedance in an RL Circuit (Resistance and Inductor)
where
Impedance in an RC Circuit (Resistance and Capacitor)
where
Power in Single-Phase Circuits
Active (Real) Power
where
Reactive Power
Apparent Power
Three-Phase AC Electricity
Three-Phase Circuits
Connection Configurations
Star (Y)
Delta (Δ)
Power in Three-Phase Circuits
Active (Real) Power
Reactive Power
Apparent Power
Power Calculation in Balanced Circuits
- In a balanced three-phase system, the power in the three phases is equal, and the total power can be calculated as: