In series circuits, current is constant throughout. Adding more resistors in series always increases total resistance, reducing circuit current. The voltage drop across each resistor follows the voltage divider rule.
⚠All resistor values must be positive. Series resistors always give higher total resistance than any individual resistor. Zero ohms is not allowed.
What is Series Resistance?
Resistors in series are connected end-to-end, forming a single path for current. The total resistance is simply the arithmetic sum of all resistor values. The same current flows through every resistor, but the voltage divides proportionally to each resistance value.
Addition Rule
Rt = R1 + R2 + ... + Rn. Simply add all values. Rt always larger than the largest individual resistor.
Voltage Divider
Voltage across each resistor is proportional to its resistance: Vn = Vt × Rn / Rt. Larger R = larger voltage drop.
Equal Resistors
n identical resistors of value R in series: Rt = n × R. Example: 3 × 100Ω = 300Ω. Voltages are equal.
Power Dissipation
Each resistor dissipates Pn = I² × Rn. Total power = sum of individual powers = I² × Rt.
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