Compute magnetomotive force (MMF) from turns and current For a coil with N = 150 turns carrying current I = 2 A, what is the magnetomotive force F = N * I (in ampere-turns)?

Difficulty: Easy

Correct Answer: 300 At

Explanation:


Introduction / Context:
Magnetomotive force (MMF) is the magnetic analog of electromotive force in circuits. It drives magnetic flux through a magnetic path and is directly proportional to the number of turns and the current through those turns. Calculating MMF is a foundational step in designing inductors, solenoids, and transformers.


Given Data / Assumptions:

  • Number of turns N = 150 turns.
  • Current I = 2 A.
  • Use F = N * I with F in ampere-turns (At).


Concept / Approach:
The greater the product of turns and current, the stronger the magnetizing force. While material properties and geometry affect resulting flux, MMF itself is purely a function of windings and current, independent of core type in the basic calculation.


Step-by-Step Solution:
Write the formula: F = N * I.Substitute: F = 150 * 2 = 300 At.Therefore, MMF = 300 ampere-turns.


Verification / Alternative check:
Units check: turns × amperes → ampere-turns; no conversions needed.


Why Other Options Are Wrong:
13.33 mAt: off by orders of magnitude; milli-At inappropriate here.75 At: corresponds to 150 * 0.5 A, not given.152 At: not any simple combination of the provided values.


Common Pitfalls:
Confusing MMF with magnetic field intensity H; H also depends on magnetic path length: H = F / l. Here only MMF is requested.


Final Answer:
300 At

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