Electrical Theory & Fundamentals Flashcards
7 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 7 Electrical Theory & Fundamentals flashcards as text
What happens to the total resistance when resistors are connected in parallel?
Answer: It is always less than the smallest resistor
In a parallel circuit, the total resistance is always less than the smallest individual resistor because current has multiple paths.
A conductor has a resistance of 10 ohms at 20°C. If the temperature increases, what happens to its resistance?
Answer: Increases, because higher temperature increases atomic vibration
For most metallic conductors, resistance increases with temperature due to increased atomic vibration impeding electron flow.
What is the unit of electrical capacitance?
Answer: Farad
The farad (F) is the SI unit of capacitance, measuring a capacitor's ability to store electric charge.
In an AC circuit, what does the term 'reactance' refer to?
Answer: Opposition to current flow by inductors or capacitors
Reactance is the opposition to AC current caused by inductance (XL) or capacitance (XC), measured in ohms but unlike resistance it stores rather than dissipates energy.
What is the relationship between frequency and inductive reactance (XL)?
Answer: XL increases as frequency increases
Inductive reactance XL = 2πfL, so it is directly proportional to frequency — as frequency increases, XL increases.
Two 100-ohm resistors are connected in parallel. What is the total resistance?
Answer: 50 ohms
For two equal resistors in parallel, total resistance = R/2 = 100/2 = 50 ohms.
What is the power factor in a purely resistive AC circuit?
Answer: 1.0
In a purely resistive circuit, voltage and current are in phase, so the power factor equals 1.0 (or unity).