Electrical Contractor Electrical Theory & Fundamentals 1 Flashcards
6 cards from real Licensed Electrical Contractor practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Electrical Contractor Electrical Theory & Fundamentals 1 flashcards as text
A 480-volt circuit draws 16 amperes of current. What is the resistance of the load?
Answer: 30 ohms
Using Ohm's Law, R = V ÷ I = 480 ÷ 16 = 30 ohms. Dividing the voltage by the current gives the resistance of the load.
Three resistors of 10 ohms, 15 ohms, and 25 ohms are connected in series to a 150-volt source. What is the current flowing through the circuit?
Answer: 3.0 amperes
In a series circuit, total resistance is the sum of all resistors: 10 + 15 + 25 = 50 ohms. Applying Ohm's Law: I = V ÷ R = 150 ÷ 50 = 3.0 amperes.
An electric motor draws 12 amperes from a 240-volt supply. What is the power consumed by the motor?
Answer: 2,880 watts
Power is calculated using P = V × I = 240 × 12 = 2,880 watts. This formula relates voltage, current, and power in a purely resistive or rated-load scenario.
What is a defining characteristic of voltage in a parallel circuit?
Answer: Voltage across each branch equals the source voltage
In a parallel circuit, all branches are connected directly across the same two nodes, so every branch sees the full source voltage regardless of its resistance.
Two 40-microfarad capacitors are connected in series. What is the total capacitance of the combination?
Answer: 20 µF
For capacitors in series, 1/C_total = 1/C1 + 1/C2 = 1/40 + 1/40 = 2/40, so C_total = 20 µF. Series capacitance behaves opposite to series resistance — it decreases.
What is the standard frequency of alternating current (AC) supplied to residential and commercial buildings in the United States?
Answer: 60 Hz
The U.S. power grid operates at 60 Hz, meaning the current completes 60 full cycles per second. Most other countries use 50 Hz as their standard frequency.