Two identical capacitors, each with capacitance C, connected in series have an equivalent capacitance equal to C/2.

• A. True
• B. False
• C. C
• D. 2C

Answer: (A)

When capacitors are in series, the total capacitance is smaller than either capacitor because the same charge must be stored on both while the voltages add up. The relationship for two capacitors in series is 1/Ceq = 1/C1 + 1/C2. If both have the same capacitance C, then 1/Ceq = 1/C + 1/C = 2/C, which gives Ceq = C/2. Hence the statement is true. This differs from the parallel case, where equal capacitors add to give 2C, so the result in series being half of C makes sense.