The total resistance in a series circuit is the sum of the individual resistances…
R= R1 + R2 + R3
R= 3 Ω + 9 Ω + 6 Ω
R= 18 Ω
The total current can be found from Ohm's law…
I= V/R
I= (12 V)/(18 Ω) = ⅔ A
I= 0.667 A
The voltage in a circuit rises in a battery and drops in a resistor (when we follow the flow of conventional current). The rise in the battery is given as 12 V and the drops in each resistor can be found through repeated use of Ohm's law…
V1 = I1R1
V1 = (⅔ A)(3 Ω)
V1 = 2 V
V2 = I2R2
V2 = (⅔ A)(9 Ω)
V2 = 6 V
V3 = I3R3
V3 = (⅔ A)(6 Ω)
V3 = 4 V
