Licensed Electrical Contractor Electrical Contractor Electrical Theory & Fundamentals 2 — Questions and Answers
Question 1: A 240-volt circuit supplies a 5,000-watt electric heater. What is the current draw of the heater?
- 20.83 amps (Correct answer)
- 25 amps
- 10.42 amps
- 41.67 amps
Correct answer: 20.83 amps
Using P = V × I, the current is 5,000 ÷ 240 = 20.83 amps.
Question 2: What is the total resistance of three 30-ohm resistors connected in parallel?
- 10 ohms (Correct answer)
- 90 ohms
- 30 ohms
- 15 ohms
Correct answer: 10 ohms
For identical resistors in parallel, total resistance equals one resistor's value divided by the number of resistors: 30 ÷ 3 = 10 ohms.
Question 3: Which type of electrical current periodically reverses direction?
- Alternating current (AC) (Correct answer)
- Direct current (DC)
- Pulsating current
- Static current
Correct answer: Alternating current (AC)
Alternating current reverses its direction of flow at regular intervals, typically 60 times per second in the US.
Question 4: In a series circuit with a 120-volt source and two equal resistors, what is the voltage drop across each resistor?
- 60 volts (Correct answer)
- 120 volts
- 30 volts
- 240 volts
Correct answer: 60 volts
In a series circuit, voltage divides proportionally, so two equal resistors each drop half the source voltage: 120 ÷ 2 = 60 volts.
Question 5: What is the power factor of a purely resistive AC circuit?
- 1.0 (Correct answer)
- 0.8
- 0.5
- 0
Correct answer: 1.0
A purely resistive load has voltage and current perfectly in phase, resulting in a power factor of 1.0 (unity).
Question 6: A conductor has a resistance of 4 ohms and carries 8 amps of current. How much power is dissipated as heat?
- 256 watts (Correct answer)
- 32 watts
- 64 watts
- 512 watts
Correct answer: 256 watts
Using P = I² × R, the power is 8² × 4 = 64 × 4 = 256 watts.
Licensed Electrical Contractor Electrical Contractor Electrical Theory & Fundamentals 2
A 240-volt circuit supplies a 5,000-watt electric heater.
What is the current draw of the heater?