Journeyman Electrician's Basic Formula Flashcards
7 cards from real Journeyman Electrician’s Exam practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Journeyman Electrician's Basic Formula flashcards as text
Two resistors of 12Ω and 6Ω are connected in parallel. What is the equivalent resistance?
Answer: 4 Ω
1/R = 1/12 + 1/6 = 1/12 + 2/12 = 3/12; R = 4 Ω.
A single-phase transformer has a primary voltage of 480V and a turns ratio of 4:1. What is the secondary voltage?
Answer: 120 V
V_secondary = V_primary / turns ratio = 480 / 4 = 120 V.
What formula is used to calculate electrical energy consumed over time?
Answer: E = P × T
Energy (in watt-hours) = Power (watts) × Time (hours).
A 10 kW load operates for 8 hours. How many kilowatt-hours (kWh) does it consume?
Answer: 80 kWh
Energy = 10 kW × 8 h = 80 kWh.
In a three-phase system, apparent power (VA) is calculated as:
Answer: VA = √3 × V_L × I_L
Three-phase apparent power = √3 × line voltage × line current.
A conductor has 0.5Ω of resistance and carries 10A. What is the power lost in the conductor?
Answer: 50 W
P = I² × R = 10² × 0.5 = 100 × 0.5 = 50 W.
What is the horsepower output of a motor drawing 746 W with 100% efficiency?
Answer: 1 HP
1 HP = 746 W, so 746 W / 746 = 1 HP.