GUIDE深度 · Deep dive
Ohm's Law and Electric Power
Ohm's law U=IR links voltage, current and resistance; electric power is P=UI. In series, current is the same and voltages add; in parallel, voltage is the same and currents add. Check units A, V, Ω, W before calculating.
Formulas
U=IR; I=U/R; R=U/I.
P=UI; P=I²R; P=U²/R.
Series/parallel
Series: Rtotal=R1+R2, same current.
Parallel: 1/Rtotal=1/R1+1/R2, same voltage.
FAQ
P=UI or P=I²R?
Use P=UI with U/I, and P=I²R with I/R.
Do I need unit conversion?
Convert mA to A and kΩ to Ω first.