10.2.4—The formula for the combined resistance of two or more resistors in series

For series resistors, the same current flows through each and total resistance is the sum of individual resistances.

Use V_total=IR_total and note that p.d. divides in proportion to resistance when current is common.

4 Ω and 6 Ω in series give 10 Ω; at 2 A the voltage drops are 8 V and 12 V.

Series components do not share equal voltage unless their resistances happen to be equal.