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FE · 5% of the exam

Electricity and Magnetism practice questions

10 free Electricity and Magnetism questions for the FE Mechanical Exam (FE) exam, each with the correct answer and an explanation for every option.

Start the questionsFree 10-question FE quiz

What this domain covers

Basic circuits and machines a mechanical engineer meets: DC and AC circuit analysis, power and electric motors.

Exam weight
5%
On a real exam
≈ 6 questions
In our bank
30 questions

Topics that come up most

  • Ohm's law and Kirchhoff's laws
  • Series and parallel equivalent circuits
  • Power and energy in circuits
  • AC circuits, phasors and power factor
  • Motors and generators

How to study it

Work a handful of circuits by reducing them to one equivalent resistance or impedance step by step; most questions start that way.

Sample Electricity and Magnetism questions

Try each one before opening the answer. Original questions written to the official exam objectives.

  1. Question 1

    A series circuit has R = 3 Ω and inductive reactance X_L = 4 Ω. The magnitude of the impedance is:

    • A12 Ω, multiplying the values
    • B7 Ω, adding the values
    • C1 Ω, the difference
    • D5 Ω
    Show answer and explanation

    Answer: D) 5 Ω

    • AIncorrect. That isn't the calculation.
    • BIncorrect. Combine them as vectors.
    • CIncorrect. That isn't the calculation.
    • DCorrect. \(\sqrt{R^2 + X_L^2}\).

  2. Question 2

    An inductor of 0.5 H carries a current of 4 A. The energy stored is:

    • A4 J
    • B8 J, omitting the 1/2
    • C1 J, using I instead of I²
    • D2 J
    Show answer and explanation

    Answer: A) 4 J

    • ACorrect. \(E = \tfrac{1}{2}LI^2\).
    • BIncorrect. The formula includes 1/2.
    • CIncorrect. Current must be squared.
    • DIncorrect. That isn't the calculation.

  3. Question 3

    A 0.2-m conductor carrying 10 A sits perpendicular to a 0.5-T magnetic field. The magnetic force on it is:

    • A1 N
    • B10 N
    • C25 N
    • D0.1 N
    Show answer and explanation

    Answer: A) 1 N

    • ACorrect. \(F = BIL = 0.5(10)(0.2)\).
    • BIncorrect. Include the length.
    • CIncorrect. Multiply, don't divide.
    • DIncorrect. Recheck the calculation.

  4. Question 4

    A balanced three-phase load draws 10 A at a line voltage of 480 V and a power factor of 0.9. The real power is about:

    • A4.32 kW
    • B7.48 kW
    • C12.96 kW
    • D8.31 kW
    Show answer and explanation

    Answer: B) 7.48 kW

    • AIncorrect. Include \(\sqrt{3}\).
    • BCorrect. \(P = \sqrt{3}V_LI_L\cos\theta\).
    • CIncorrect. Use \(\sqrt{3}\), not 3.
    • DIncorrect. Apply the power factor.

  5. Question 5

    A 0.1-H inductor operates at 60 Hz. Its inductive reactance is about:

    • A6.0 Ω
    • B37.7 Ω
    • C0.027 Ω
    • D377 Ω
    Show answer and explanation

    Answer: B) 37.7 Ω

    • AIncorrect. Include 2π.
    • BCorrect. \(X_L = 2\pi fL\).
    • CIncorrect. That's inverted.
    • DIncorrect. Recheck the calculation.

  6. Question 6

    Kirchhoff's current law states that at any node:

    • AResistance is constant
    • BThe voltages around a loop sum to zero
    • CThe currents sum to zero
    • DPower is maximized
    Show answer and explanation

    Answer: C) The currents sum to zero

    • AIncorrect. It concerns currents at a node.
    • BIncorrect. That's Kirchhoff's voltage law.
    • CCorrect. Current in equals current out.
    • DIncorrect. It concerns currents at a node.

  7. Question 7

    Resistors of 4 Ω, 6 Ω, and 12 Ω are connected in parallel across a DC source. What is the equivalent resistance of the combination?

    • A2.0 Ω
    • B22 Ω
    • C7.3 Ω
    • D4.0 Ω
    Show answer and explanation

    Answer: A) 2.0 Ω

    For resistors in parallel, the reciprocals add: 1/R_eq = Σ(1/R_i). Here that gives 2.0 Ω, which is less than the smallest branch resistance.

    • ACorrect. 1/R_eq = 1/4 + 1/6 + 1/12 = 3/12 + 2/12 + 1/12 = 6/12, so R_eq = 2.0 Ω.
    • BIncorrect. 22 Ω is the sum of the resistances, which is the series equivalent and not the parallel one.
    • CIncorrect. 7.3 Ω is the average of the three resistances, and that has no meaning for a parallel connection.
    • DIncorrect. The parallel equivalent is always smaller than the smallest branch resistance, so it must be less than 4 Ω.

  8. Question 8

    A single-phase load draws 10 A rms at 120 V rms with a power factor of 0.8. The real power is:

    • A1,500 W
    • B1,200 W
    • C960 W
    • D720 W
    Show answer and explanation

    Answer: C) 960 W

    • AIncorrect. Multiply by the power factor.
    • BIncorrect. That's apparent power in VA.
    • CCorrect. \(P = VI\cos\theta = 120(10)(0.8)\).
    • DIncorrect. Recheck the calculation.

  9. Question 9

    A 100-μF capacitor is charged to 100 V. The stored energy is:

    • A0.01 J
    • B1.0 J
    • C0.5 J
    • D5,000 J
    Show answer and explanation

    Answer: C) 0.5 J

    • AIncorrect. Square the voltage.
    • BIncorrect. Include the ½ factor.
    • CCorrect. \(\tfrac{1}{2}CV^2 = \tfrac{1}{2}(10^{-4})(10^4)\).
    • DIncorrect. Use C in farads.

  10. Question 10

    In a balanced three-phase wye-connected system, the phase (line-to-neutral) voltage is 230 V. The line-to-line voltage is about:

    • A230 V
    • B398 V
    • C133 V
    • D690 V
    Show answer and explanation

    Answer: B) 398 V

    In a balanced wye connection, the line-to-line voltage is √3 times the phase voltage: √3 × 230 V ≈ 398 V.

    • AIncorrect. Line and phase voltages are equal in a delta connection, not in a wye connection.
    • BCorrect. In a balanced wye, V_line = √3 × V_phase = 1.732 × 230 V ≈ 398 V.
    • CIncorrect. This divides by √3 instead of multiplying. The line voltage is larger than the phase voltage in a wye.
    • DIncorrect. This multiplies by 3 instead of √3.

Electricity and Magnetism: FAQs

How much of the FE exam is Electricity and Magnetism?

Electricity and Magnetism is 5% of the FE exam by the official exam guide's weighting, which on a 110-question form works out to roughly 6 questions. The real exam's exact split varies by form.

What does the Electricity and Magnetism domain cover?

Basic circuits and machines a mechanical engineer meets: DC and AC circuit analysis, power and electric motors.

How should I study Electricity and Magnetism for FE?

Work a handful of circuits by reducing them to one equivalent resistance or impedance step by step; most questions start that way.

Where can I practise more Electricity and Magnetism questions?

This page has 10 free Electricity and Magnetism questions with answers. The ExamWize FE question bank has 30 questions in this domain. Every practice exam result breaks your score down by domain, and Review Mode re-drills the questions you missed.

Other FE topics

Also: 15 free questions across all topics, the FE cheat sheet and the study guide.

Get Electricity and Magnetism exam-ready

The full FE bank has 30 Electricity and Magnetism questions. Timed practice exams match the real exam's length and domain weights, every result shows your score per domain, and Review Mode re-drills the questions you missed.

See the full FE practice examsTake the free diagnostic

Not affiliated with NCEES; questions are original, written from the official exam outline, and never copied from the real exam.