Which of the following statements is correct? When capacitors of different values are connected in series

Question analysis: The question asks what is true when capacitors of different values are connected in series.

Concept: In a series connection, the capacitors sit along a single path with no branches. Any charge that leaves one plate must go to the next capacitor, so the same current flows for the same time through each one. Each capacitor therefore stores the same charge Q.

The voltage across each capacitor is given by V = Q/C. Since Q is the same but the capacitances differ, the voltages are different. A smaller capacitor has a larger voltage across it.

Step by step:

1. Series connection means the same charge Q on every capacitor.
2. V₁ = Q/C₁, V₂ = Q/C₂, V₃ = Q/C₃, so the voltages are different when the C values are different.
3. The total voltage is V = V₁ + V₂ + V₃, and the equivalent capacitance is 1/C = 1/C₁ + 1/C₂ + 1/C₃.

Checking the options:

• A. The same charge flows through them. This is correct.
• B. The same voltage across each. This is wrong, because the voltage is the same in a parallel connection, not in series.
• C. Different charges with different voltages. The different voltages are right, but the different charges are wrong.
• D. Different charges with the same voltage. This is wrong on both counts.

Answer: A

Exam tip: Remember "Series = Same charge" and "Parallel = Potential difference (voltage) is the same". This is the opposite of resistors, where current is the same in series and voltage is the same in parallel. Capacitors in series have the same charge in the same way that resistors in series have the same current.