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
A 240V circuit draws 15A. What is the power consumed in watts?
Answer: 3,600 W
P = V × I = 240 × 15 = 3,600 W.
Using Ohm's Law, what is the current through a 48Ω resistor connected to a 120V source?
Answer: 2.5 A
I = V / R = 120 / 48 = 2.5 A.
What is the resistance of a device that draws 4A from a 240V source?
Answer: 60 Ω
R = V / I = 240 / 4 = 60 Ω.
A motor operates at 480V and 20A with a power factor of 0.85. What is the true (real) power in watts?
Answer: 8,160 W
P = V × I × PF = 480 × 20 × 0.85 = 8,160 W.
Three resistors of 10Ω, 20Ω, and 30Ω are connected in series. What is the total resistance?
Answer: 60 Ω
In series, R_total = R1 + R2 + R3 = 10 + 20 + 30 = 60 Ω.
What is the voltage drop across a 25Ω load carrying 3A?
Answer: 75 V
V = I × R = 3 × 25 = 75 V.
A circuit uses 4,800 W at 120V. What size breaker (in amps) is the minimum required at 125% of load?
Answer: 50 A
I = P / V = 4,800 / 120 = 40 A; 40 × 1.25 = 50 A minimum breaker.