FORMULAS

Ohm's Law for DC Circuits

Current: I = E/R = P/E
Voltage: E = I*R = P/I
Resistance: R = E/I = P/(I*I) = (E*E)/P
Power: P = (I*I)*R = E*I = (E*E)/R

Resistors in Series and Parallel

Series: R = R1 + R2 + R3 + . . .
Parallel: R = 1/( 1/R1 + 1/R2 + 1/R3 + . . .)

Conductors in Series and Parallel

Series: G = 1/( 1/G1 + 1/G2 + 1/G3 + . . . )
Parallel: G = G1 + G2 + G3 + . . .

Resistors and Conductors

Resistance: R = 1/G
Conductance: G = 1/R