Electrical Engineering Fundamentals

Ohm's law states that V = IR, where V is voltage (volts), I is current (amps), and R is resistance (ohms).

I = V / R. Current equals voltage divided by resistance.

R = V / I. Resistance equals voltage divided by current.

The ohm (Ω), named after Georg Simon Ohm.

P = VI, where P is power in watts, V is voltage, and I is current.

P = I²R or P = V²/R, derived by substituting Ohm's law into P = VI.

The sum of all currents entering a node equals the sum of all currents leaving that node: ΣI_in = ΣI_out.

The sum of all voltage drops around any closed loop in a circuit equals zero: ΣV = 0.

Conservation of charge — charge cannot accumulate at a node in a circuit.

Conservation of energy — the total energy gained equals the total energy lost around a closed loop.

DC (direct current) flows in one constant direction; AC (alternating current) periodically reverses direction.

60 Hz. The voltage alternates at 60 cycles per second.