DC Circuit Analysis & Theory Flashcards
7 cards from real CET practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 DC Circuit Analysis & Theory flashcards as text
Three resistors of 10 Ω, 20 Ω, and 30 Ω are connected in series across a 120 V supply. What is the voltage drop across the 20 Ω resistor?
Answer: 40 V
Total resistance is 60 Ω; current = 2 A; V = 2 A × 20 Ω = 40 V.
Which law states that the algebraic sum of all voltages around any closed loop in a circuit equals zero?
Answer: Kirchhoff's Voltage Law
Kirchhoff's Voltage Law (KVL) states that the sum of EMFs equals the sum of voltage drops around any closed loop.
A 60 W lamp operates at 120 V. What is its resistance?
Answer: 240 Ω
R = V²/P = 120²/60 = 14400/60 = 240 Ω.
In a voltage divider with R1 = 4 kΩ and R2 = 1 kΩ connected to 25 V, what is the output voltage across R2?
Answer: 5 V
Vout = Vin × R2/(R1+R2) = 25 × 1/5 = 5 V.
What happens to total resistance when additional resistors are added in series?
Answer: Increases
Series resistances add directly, so total resistance always increases with each addition.
A circuit has a 9 V battery and a 3 Ω internal resistance with a 6 Ω external load. What current flows through the circuit?
Answer: 1 A
I = V / (r + R) = 9 / (3 + 6) = 9/9 = 1 A.
Power dissipated in a resistor doubles when the current through it is:
Answer: Increased by √2
P = I²R, so to double P, I must increase by √2 since (√2)² = 2.