Deep Dive: G5C11
The correct answer is C: 70 millihenries. The inductance of a circuit with a 20-millihenry inductor connected in series with a 50-millihenry inductor is 70 millihenries. Series inductance adds directly: Ltotal = 20 + 50 = 70 mH. For amateur radio operators, this is a basic series inductance calculation. Understanding this helps when analyzing series inductors.
Why Other Answers Are Wrong
Option A (7 millihenries): Incorrect. 7 mH is too low - that would be if inductances were in parallel, not series. Series inductors add, not use reciprocal formula. Option B (14.3 millihenries): Incorrect. 14.3 mH is too low - that would be if using parallel formula. Series inductors add directly. Option D (1,000 millihenries): Incorrect. 1,000 mH = 1 henry, which is way too high. That would be 20 × 50, not 20 + 50. Calculation error.
Exam Tip
Series inductance: L = 20 + 50 = 70 mH. Think 'S'eries 'L'nductors = 'S'um directly. Series inductors add directly, like resistors. Not 7 mH (parallel), not 14.3 mH (parallel), not 1000 mH (product) - just 70 mH.
Memory Aid
Series inductance: L = 20 + 50 = 70 mH. Think 'S'eries 'L'nductors = 'S'um directly. Series inductors add directly, like series resistors. Standard series calculation.
Real-World Example
Two inductors in series: 20 mH and 50 mH. Total inductance = 20 + 50 = 70 millihenries. Series inductors add directly, just like series resistors. This is different from parallel inductors, which use the reciprocal formula.
Source & Coverage
Question Pool: 2023-2027 Question Pool
Subelement: G5C
Reference: 2023-2027 Question Pool · G5 - Electrical Principles
Key Concepts
Verified Content
Question from the official FCC General Class pool. Explanation reviewed by licensed amateur radio operators and mapped to the G5C topic.