FAA Aviation Mechanic General (AMG)Fundamentals of Electricity and ElectronicsMedium
A technician measures a coil with an inductance of 0.5 henry connected to a 60 Hz AC power source. What is the inductive reactance of the coil?
- A30 ohms
- B376 ohms
- C94 ohms
- D188 ohms
Show answer & explanationAnswer & explanation
Correct answer: D. 188 ohms
Inductive reactance is calculated as XL = 2πfL. Substituting values: XL = 2 × 3.14 × 60 × 0.5 = 188.4 ohms, which rounds to 188 ohms.
Why the other options are wrong
- A. This value is too low; it does not use the correct formula.
- B. This is double the correct value, likely from an arithmetic error.
- C. This is half the correct value, possibly from omitting a factor of 2.
Inductive Reactance (XL)
The opposition an inductor presents to AC current flow, which increases with frequency and inductance.
- Formula: XL = 2πfL
- Directly proportional to frequency and inductance
- Measured in ohms
Memory trick: Inductors 'resist change' more as frequency climbs — XL rises with f and L.