Series capacitors voltage division: In a purely series capacitive chain, does the smallest capacitance experience the largest voltage drop for a given charge?
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ACorrect
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BIncorrect
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COnly true if leakage is zero
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DOnly true for identical dielectric materials
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EOnly true at DC, not AC
Answer
Correct Answer: Correct
Explanation
Introduction / Context:Voltage division across series capacitors follows the inverse relation to capacitance values. Because series capacitors carry the same charge, the voltage across each is determined by V_i = Q / C_i. This principle is essential when designing capacitive dividers or placing series capacitors across high-voltage rails for rating purposes.
Given Data / Assumptions:
- Ideal series connection, same current and hence same charge magnitude on each element.
- Negligible leakage and identical steady-state charge distribution.
- Sinusoidal or DC conditions where reactive steady state is reached.
Concept / Approach:In series, Q is common to all capacitors. Therefore V_i = Q / C_i: a smaller C produces a larger V_i. The total applied voltage divides inversely with capacitance values. Designers often include voltage-balancing resistors in high-voltage stacks to mitigate imbalance due to leakage and tolerances.
Step-by-Step Solution:
State series rule: same charge on all capacitors.Compute V_i = Q / C_i for each element.Compare voltages: the smallest C has the largest V_i.Therefore, the statement is correct.Verification / Alternative check:AC phasor analysis also shows larger magnitude across the smaller capacitance because Xc = 1 / (2 * pi * f * C) is larger, yielding a larger share of the phasor drop.
Why Other Options Are Wrong:
Incorrect or conditional options add constraints that are not required by the ideal series rule.Common Pitfalls:Ignoring leakage and tolerance which can distort division in practice; forgetting to add balancing networks in HV applications.
Final Answer:Correct