How long does one complete cycle of a 60 Hz waveform take?
Answer in ms.
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16.67 ms
Period T = 1 ÷ f = 1 ÷ 60 = 0.01667 s. 0.01667 s × 1,000 = 16.67 ms.
Reference: AC fundamentals: period T = 1 ÷ f
Electrical Theory & Calculations Practice Test
Ohm's law, power, series and parallel circuits, AC theory, three-phase, transformers and motors: the math and theory questions on journeyman and master electrician exams.
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Mixed practice test
10 questions, graded as you go, with the reason for every answer. No sign-up.
Timed mock exam
50 questions in 60 minutes, drawn from every topic. No answers shown until the end, then a score, your weakest topics and a review of what you missed.
Practise by topic
- AC theory 30 questions
- Motors misc 25 questions
- Ohm's law power 35 questions
- Series parallel 30 questions
- Three phase 25 questions
- Transformers 25 questions
Sample questions
A motor delivers 10 hp at its shaft. What is its output power in watts? (1 hp = 746 W)
Answer in W.
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7460 W
Output = hp × 746 = 10 × 746 = 7,460 W.
Reference: Unit conversion: 1 hp = 746 W
A heating element with a resistance of 24 Ω is connected to a 120 V source. How much current does it draw?
Answer in A.
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5 A
I = E ÷ R = 120 V ÷ 24 Ω = 5 A.
Reference: Ohm's law, I = E ÷ R
Resistors of 10 Ω, 20 Ω and 30 Ω are connected in series. What is the total resistance?
Answer in Ω.
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60 Ω
RT = R1 + R2 + R3 = 10 + 20 + 30 = 60 Ω.
Reference: Series circuit rule: RT = R1 + R2 + R3
Which statement is true of a balanced wye-connected source or load?
- Line voltage equals phase voltage, and line current is 1.732 times phase current
- Line voltage and line current are both 1.732 times the phase values
- Line voltage and line current are both equal to the phase values
- Line voltage is 1.732 times phase voltage, and line current equals phase current
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D. Line voltage is 1.732 times phase voltage, and line current equals phase current
In a wye, each line conductor is in series with one winding, so line and phase current are the same, while two windings 120° apart are between any two lines, making line voltage 1.732 × phase voltage. The first wrong choice describes a delta.
Reference: Wye connection: E line = 1.732 × E phase; I line = I phase
Exams this helps with
| Exam | Who runs it | Where |
|---|---|---|
| Journeyman electrician ready | State boards (PSI, Prov, ICC, Pearson VUE) | United States (varies by state) |
| Master electrician ready | State boards | United States (varies by state) |
| Residential wireman / residential electrician ready | State boards | United States (varies by state) |
| Electrical Levels 1 to 4 module tests ready | NCCER | United States |