General Theory and Calculations Flashcards
7 cards from real PC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 General Theory and Calculations flashcards as text
A 240V single-phase circuit draws 15A. What is the apparent power in VA?
Answer: 3,600 VA
Apparent power S = V × I = 240V × 15A = 3,600 VA.
Which formula correctly expresses Ohm's Law for current?
Answer: I = V / R
Ohm's Law states I = V / R, where I is current, V is voltage, and R is resistance.
Three resistors of 6Ω, 12Ω, and 4Ω are connected in parallel. What is the total equivalent resistance?
Answer: 2 Ω
1/R_T = 1/6 + 1/12 + 1/4 = 2/12 + 1/12 + 3/12 = 6/12, so R_T = 2Ω.
What is the power factor of a purely resistive AC circuit?
Answer: 1.0
A purely resistive circuit has zero phase angle between V and I, so PF = cos(0°) = 1.0.
A conductor has a resistance of 0.5Ω and carries 20A. What is the power dissipated as heat?
Answer: 200 W
P = I² × R = (20)² × 0.5 = 400 × 0.5 = 200 W.
In a series RLC circuit at resonance, which statement is true?
Answer: Inductive and capacitive reactances are equal and cancel
At resonance, XL = XC, they cancel, and the circuit impedance equals resistance only.
What does a lagging power factor indicate about a load?
Answer: The load is predominantly inductive
A lagging power factor means current lags behind voltage, which is characteristic of inductive loads.