In a circuit with capacitors connected in series, how does the total capacitance compare to the individual capacitors?

• A. Increases
• B. Decreases
• C. Remains the Same
• D. Zero

Answer: (B)

When capacitors are in series, the same amount of charge must be stored on each one, so the charge Q is the same for every capacitor. The total voltage across the chain is the sum of the individual voltages, with each voltage given by Vi = Q / Ci. Therefore V_total = Q × sum(1/Ci). The equivalent capacitance is C_eq = Q / V_total = 1 / sum(1/Ci). Since the sum of reciprocals is larger than any single reciprocal, C_eq is smaller than any individual capacitance. Adding more capacitors in series thus lowers the total capacitance (for two identical caps, it becomes C/2). This is in contrast to capacitors in parallel, where the capacitances add and the total increases.