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 