Journeyman Electricianâs Exam Journeyman Electrician's Basic Formula 2 â Questions and Answers
Question 1: A 240V circuit draws 15A. What is the power consumed in watts?
- 1,800 W
- 3,600 W (Correct answer)
- 240 W
- 255 W
Correct answer: 3,600 W
P = V Ă I = 240 Ă 15 = 3,600 W.
Question 2: Using Ohm's Law, what is the current through a 48Ω resistor connected to a 120V source?
- 5,760 A
- 72 A
- 2.5 A (Correct answer)
- 0.4 A
Correct answer: 2.5 A
I = V / R = 120 / 48 = 2.5 A.
Question 3: What is the resistance of a device that draws 4A from a 240V source?
- 960 Ω
- 60 Ω (Correct answer)
- 0.017 Ω
- 236 Ω
Correct answer: 60 Ω
R = V / I = 240 / 4 = 60 Ω.
Question 4: A motor operates at 480V and 20A with a power factor of 0.85. What is the true (real) power in watts?
- 9,600 W
- 8,160 W (Correct answer)
- 11,294 W
- 480 W
Correct answer: 8,160 W
P = V Ă I Ă PF = 480 Ă 20 Ă 0.85 = 8,160 W.
Question 5: Three resistors of 10Ω, 20Ω, and 30Ω are connected in series. What is the total resistance?
- 5.45 Ω
- 60 Ω (Correct answer)
- 300 Ω
- 20 Ω
Correct answer: 60 Ω
In series, R_total = R1 + R2 + R3 = 10 + 20 + 30 = 60 Ω.
Question 6: What is the voltage drop across a 25Ω load carrying 3A?
- 8.33 V
- 75 V (Correct answer)
- 22 V
- 28 V
Correct answer: 75 V
V = I Ă R = 3 Ă 25 = 75 V.
Question 7: A circuit uses 4,800 W at 120V. What size breaker (in amps) is the minimum required at 125% of load?
- 40 A
- 50 A (Correct answer)
- 60 A
- 30 A
Correct answer: 50 A
I = P / V = 4,800 / 120 = 40 A; 40 Ă 1.25 = 50 A minimum breaker.
Journeyman Electricianâs Exam Journeyman Electrician's Basic Formula 2
A 240V circuit draws 15A.
What is the power consumed in watts?