Updated: Dec 9, 2025 | Source: 2023-2027 Question Pool | Topic: G5C
G5C10G5C

What is the inductance of three 10-millihenry inductors connected in parallel?

Deep Dive: G5C10

The correct answer is C: 3.3 millihenries. The inductance of three 10-millihenry inductors connected in parallel is 3.3 millihenries. 1/Ltotal = 1/10 + 1/10 + 1/10 = 3/10 = 0.3. Ltotal = 1/0.3 = 3.33 mH ≈ 3.3 mH. For amateur radio operators, this is a basic parallel inductance calculation. Understanding this helps when analyzing parallel inductors.

Why Other Answers Are Wrong

Option A (0.30 henries): Incorrect. 0.30 henries = 300 mH, which is too high. Answer should be in millihenries, not henries. Unit error. Option B (3.3 henries): Incorrect. 3.3 henries = 3,300 mH, which is way too high. Answer should be in millihenries, not henries. Unit error. Option D (30 millihenries): Incorrect. 30 mH is the sum (series), not parallel. Parallel inductance is less than individual inductors.

Exam Tip

Parallel inductance: 1/L = 1/10 + 1/10 + 1/10 = 0.3, L = 1/0.3 = 3.3 mH. Think 'P'arallel 'L'nductors = 'P'reciprocal sum, then 'R'eciprocal. Use 1/Ltotal = 1/L1 + 1/L2 + 1/L3. Answer in millihenries, not henries. Not 0.30H, not 3.3H, not 30 mH (sum) - just 3.3 mH.

Memory Aid

Parallel inductance: 1/L = 0.3, L = 3.3 mH. Think 'P'arallel 'L'nductors = 'P'reciprocal sum. Use 1/Ltotal = 1/L1 + 1/L2 + 1/L3, then take reciprocal. Answer in millihenries. Standard parallel calculation.

Real-World Example

Three inductors in parallel: 10 mH each. 1/Ltotal = 1/10 + 1/10 + 1/10 = 3/10 = 0.3. Ltotal = 1/0.3 = 3.33 millihenries ≈ 3.3 millihenries. Parallel inductance is less than individual inductors (3.3 < 10).

Source & Coverage

Question Pool: 2023-2027 Question Pool

Subelement: G5C

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

Key Concepts

Parallel inductors Total inductance Reciprocal sum Parallel circuit

Verified Content

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