D.C. CIRCUITS

Parrallel	Series
The sum of the two currents (I1 and I2) is equal to the currant in the rest of the circuit I. From the definition of resistance, I = V / R. so V / R = V / R1 + V / R2, elimating V 1 / R = 1 / R1 + 1 / R2	The sum of the two p.d.s (V1 and V2) is equal to the p.d. across both. From the definition of resistance, V = I R. So I R = I R1 + I R2, eliminating I, R = R1 + R2.