PC Electrical Theory & Principles 2 — Questions and Answers
Question 1: A series circuit has resistors of 10Ω, 20Ω, and 30Ω connected to a 120V source. What is the total current in the circuit?
- 1A
- 2A (Correct answer)
- 4A
- 6A
Correct answer: 2A
Total resistance = 10+20+30 = 60Ω; I = V/R = 120/60 = 2A.
Question 2: Which of the following best describes the relationship between power, voltage, and current in a DC circuit?
- P = V/I
- P = V × I (Correct answer)
- P = I/V
- P = V + I
Correct answer: P = V × I
Power (watts) equals voltage (volts) multiplied by current (amperes): P = V × I.
Question 3: In a series circuit, if one resistor increases in value, the total current will:
- Increase
- Remain the same
- Decrease (Correct answer)
- Double
Correct answer: Decrease
Higher resistance in a series circuit increases total resistance, reducing current per Ohm's Law.
Question 4: A 1,500W electric heater is connected to a 120V circuit. What is the operating current?
- 8A
- 10A
- 12.5A (Correct answer)
- 15A
Correct answer: 12.5A
I = P/V = 1,500/120 = 12.5A.
Question 5: Kirchhoff's Voltage Law (KVL) states that the algebraic sum of all voltages around any closed loop is:
- Equal to the source voltage
- Zero (Correct answer)
- Equal to the largest resistor drop
- Infinite
Correct answer: Zero
KVL states that the sum of all voltage rises and drops around any closed loop must equal zero.
Question 6: What is the resistance of a conductor if 5A flows through it when 25V is applied?
- 0.2Ω
- 5Ω (Correct answer)
- 125Ω
- 30Ω
Correct answer: 5Ω
R = V/I = 25/5 = 5Ω.
Question 7: Which statement about voltage drops in a series circuit is correct?
- All resistors have equal voltage drops
- Voltage drops are proportional to resistance values (Correct answer)
- The largest resistor has the smallest voltage drop
- Voltage drop is independent of resistance
Correct answer: Voltage drops are proportional to resistance values
In a series circuit, voltage drops are proportional to each resistor's value relative to total resistance.
PC Electrical Theory & Principles 2
A series circuit has resistors of 10Ω, 20Ω, and 30Ω connected to a 120V source.
What is the total current in the circuit?