What is the inductance of three 10-millihenry inductors connected in parallel?
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.
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 Application
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).
Key Concepts
Why Other Options 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.
题目解析
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.
考试技巧
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.
记忆口诀
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.
实际应用示例
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).
错误选项分析
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.
知识点
Parallel inductors, Total inductance, Reciprocal sum, Parallel circuit
Verified Content
Question from official FCC General Class question pool. Explanation reviewed by licensed amateur radio operators.