Updated: Dec 9, 2025 | Source: 2023-2027 Question Pool | Topic: G5C
G5C09G5C

What is the capacitance of three 100-microfarad capacitors connected in series?

Deep Dive: G5C09

The correct answer is C: 33.3 microfarads. The capacitance of three 100-microfarad capacitors connected in series is 33.3 microfarads. 1/Ctotal = 1/100 + 1/100 + 1/100 = 3/100 = 0.03. Ctotal = 1/0.03 = 33.3 µF. For amateur radio operators, this is a basic series capacitance calculation. Understanding this helps when analyzing series capacitors.

Why Other Answers Are Wrong

Option A (0.33 microfarads): Incorrect. 0.33 µF is too low - that would be if capacitance was divided by 300, not 3. Calculation error. Option B (3.0 microfarads): Incorrect. 3.0 µF is too low - series capacitance is less than individual, but 100/3 = 33.3, not 3.0. Calculation error. Option D (300 microfarads): Incorrect. 300 µF is the sum (parallel), not series. Series capacitance is less than individual capacitors.

Exam Tip

Series capacitance: 1/C = 1/100 + 1/100 + 1/100 = 3/100 = 0.03, C = 1/0.03 = 33.3 µF. Think 'S'eries 'C'apacitors = 'S'um of 'R'eciprocals, then 'R'eciprocal. Use 1/Ctotal = 1/C1 + 1/C2 + 1/C3. Not 0.33 µF, not 3.0 µF, not 300 µF (sum) - just 33.3 µF.

Memory Aid

Series capacitance: 1/C = 3/100 = 0.03, C = 33.3 µF. Think 'S'eries 'C'apacitors = 'S'um of 'R'eciprocals. Use 1/Ctotal = 1/C1 + 1/C2 + 1/C3, then take reciprocal. Standard series calculation.

Real-World Example

Three capacitors in series: 100 µF each. 1/Ctotal = 1/100 + 1/100 + 1/100 = 3/100 = 0.03. Ctotal = 1/0.03 = 33.3 microfarads. Series capacitance is less than individual capacitors (33.3 < 100).

Source & Coverage

Question Pool: 2023-2027 Question Pool

Subelement: G5C

Reference: 2023-2027 Question Pool · G5 - Electrical Principles

Key Concepts

Series capacitors Total capacitance Reciprocal sum Series circuit

Verified Content

Question from the official FCC General Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the G5C topic.