Circuit Theory MCQ & Objective Questions
Circuit Theory is a fundamental topic in electrical engineering and physics that plays a crucial role in various school and competitive exams. Mastering this subject not only enhances your understanding of electrical circuits but also boosts your exam scores. Practicing MCQs and objective questions helps you identify important concepts and improves your problem-solving skills, making it easier to tackle exam preparation effectively.
What You Will Practise Here
Basic concepts of circuit elements: resistors, capacitors, and inductors
Ohm's Law and its applications in circuit analysis
Series and parallel circuits: calculations and characteristics
KVL (Kirchhoff's Voltage Law) and KCL (Kirchhoff's Current Law)
Thevenin's and Norton's Theorems for circuit simplification
AC and DC circuit analysis techniques
Power calculations in electrical circuits
Exam Relevance
Circuit Theory is a significant topic in various examinations, including CBSE, State Boards, NEET, and JEE. Students can expect questions that test their understanding of circuit components, laws, and theorems. Common question patterns include numerical problems, conceptual MCQs, and application-based scenarios that require a solid grasp of the subject. Familiarity with these patterns can greatly enhance your performance in exams.
Common Mistakes Students Make
Confusing series and parallel circuit calculations
Misapplying Ohm's Law in complex circuits
Overlooking the significance of units in calculations
Neglecting to apply Kirchhoff's Laws correctly
Failing to simplify circuits using Thevenin's and Norton's Theorems
FAQs
Question: What are the key formulas I should remember for Circuit Theory?Answer: Important formulas include Ohm's Law (V = IR), power formulas (P = VI), and the rules for series and parallel resistances.
Question: How can I improve my Circuit Theory problem-solving skills?Answer: Regular practice of Circuit Theory MCQ questions and understanding the underlying concepts will significantly enhance your skills.
Start solving practice MCQs today to solidify your understanding of Circuit Theory and prepare effectively for your exams. Remember, consistent practice is the key to success!
Q. What is the Thevenin equivalent circuit for a 10V battery in series with a 5Ω resistor and a 10Ω load resistor?
A.
10V, 5Ω
B.
5V, 10Ω
C.
10V, 10Ω
D.
5V, 5Ω
Show solution
Solution
Thevenin equivalent voltage is the same as the source voltage, and the equivalent resistance is the series resistance.
Correct Answer:
A
— 10V, 5Ω
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Q. What is the Thevenin equivalent of a circuit?
A.
A single voltage source and series resistance
B.
A single current source and parallel resistance
C.
A combination of capacitors
D.
A complex impedance
Show solution
Solution
The Thevenin equivalent circuit is represented by a single voltage source in series with a resistance, simplifying the analysis of the circuit.
Correct Answer:
A
— A single voltage source and series resistance
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Q. What is the Thevenin equivalent resistance (Rth) seen from terminals A and B if there are two resistors (4Ω and 6Ω) in series?
Show solution
Solution
Rth = R1 + R2 = 4Ω + 6Ω = 10Ω.
Correct Answer:
D
— 10Ω
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Q. What is the Thevenin equivalent resistance seen by the load in a circuit with two resistors (4Ω and 6Ω) in series?
Show solution
Solution
Rth = R1 + R2 = 4Ω + 6Ω = 10Ω.
Correct Answer:
D
— 10Ω
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Q. What is the Thevenin equivalent voltage (Vth) across terminals A and B if V1 = 10V and R1 = 5Ω, R2 = 10Ω in series?
A.
10V
B.
5V
C.
15V
D.
0V
Show solution
Solution
In a series circuit, the Thevenin voltage is the same as the source voltage, so Vth = V1 = 10V.
Correct Answer:
A
— 10V
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Q. What is the Thevenin equivalent voltage (Vth) across terminals A and B in a circuit with a 10V source and a 2Ω resistor in series with a 4Ω resistor?
A.
10V
B.
7.5V
C.
5V
D.
2.5V
Show solution
Solution
Thevenin voltage is calculated using voltage division: Vth = 10V * (4Ω / (2Ω + 4Ω)) = 10V * (4/6) = 6.67V.
Correct Answer:
B
— 7.5V
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Q. What is the Thevenin equivalent voltage (Vth) in a circuit with a 10V source and a 2Ω resistor in series with a 4Ω load?
A.
10V
B.
7.5V
C.
5V
D.
2.5V
Show solution
Solution
Vth = Vsource * (Rload / (Rseries + Rload)) = 10V * (4Ω / (2Ω + 4Ω)) = 10V * (4/6) = 7.5V.
Correct Answer:
B
— 7.5V
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Q. What is the Thevenin equivalent voltage across a 10Ω resistor in series with a 20V battery?
A.
20V
B.
10V
C.
30V
D.
0V
Show solution
Solution
The Thevenin equivalent voltage is the open-circuit voltage across the terminals, which is equal to the battery voltage, 20V.
Correct Answer:
A
— 20V
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Q. What is the Thevenin equivalent voltage across a 5Ω resistor in a circuit with a 10V source and a 10Ω resistor in series?
A.
10V
B.
5V
C.
15V
D.
0V
Show solution
Solution
The voltage across the 5Ω resistor is half of the total voltage due to the voltage divider rule: V_th = 10V * (5Ω / (5Ω + 10Ω)) = 10V * (1/3) = 3.33V.
Correct Answer:
B
— 5V
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Q. What is the Thevenin equivalent voltage across a load resistor if the circuit has a 15V source and two resistors (5Ω and 10Ω) in series?
A.
5V
B.
10V
C.
15V
D.
20V
Show solution
Solution
Vth = Vsource * (Rload / (Rseries + Rload)); assuming Rload = 10Ω, Vth = 15V * (10Ω / (5Ω + 10Ω)) = 10V.
Correct Answer:
B
— 10V
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Q. What is the Thevenin equivalent voltage across a load resistor if the open-circuit voltage is 15V?
A.
0V
B.
15V
C.
30V
D.
7.5V
Show solution
Solution
The Thevenin equivalent voltage is equal to the open-circuit voltage, which is 15V.
Correct Answer:
B
— 15V
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Q. What is the Thevenin equivalent voltage across a load resistor in a simple circuit with a 12 V source and a 4 ohm resistor in series with a 2 ohm load?
A.
12 V
B.
8 V
C.
6 V
D.
4 V
Show solution
Solution
The Thevenin equivalent voltage is the voltage across the load resistor, which can be found using voltage division: V_load = V_source * (R_load / (R_series + R_load)) = 12 V * (2 / (4 + 2)) = 8 V.
Correct Answer:
B
— 8 V
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Q. What is the Thevenin equivalent voltage across a load resistor in a simple circuit?
A.
The open-circuit voltage
B.
The short-circuit current
C.
The total current
D.
The total resistance
Show solution
Solution
The Thevenin equivalent voltage is the open-circuit voltage across the load resistor when it is removed from the circuit.
Correct Answer:
A
— The open-circuit voltage
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Q. What is the Thevenin equivalent voltage across a load resistor in a simple circuit with a 12 V battery and a 4 ohm resistor in series?
A.
12 V
B.
6 V
C.
4 V
D.
0 V
Show solution
Solution
The Thevenin equivalent voltage is the same as the source voltage, which is 12 V.
Correct Answer:
A
— 12 V
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Q. What is the Thevenin equivalent voltage across a load resistor in a simple circuit with a 12V source and a 4Ω resistor in series?
Show solution
Solution
The Thevenin equivalent voltage is the open-circuit voltage, which is the source voltage, 12V.
Correct Answer:
C
— 12V
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Q. What is the Thevenin equivalent voltage across terminals A and B if a 12V battery is connected in series with a 4Ω resistor?
Show solution
Solution
The Thevenin equivalent voltage is the open-circuit voltage across terminals A and B, which is equal to the source voltage, 12V.
Correct Answer:
A
— 12V
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Q. What is the Thevenin equivalent voltage across terminals A and B in a circuit with a 10V source and a 5Ω resistor in series with a 10Ω resistor?
A.
10V
B.
6.67V
C.
5V
D.
15V
Show solution
Solution
The voltage across the 10Ω resistor is V = (10V * 10Ω) / (5Ω + 10Ω) = 6.67V.
Correct Answer:
B
— 6.67V
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Q. What is the Thevenin equivalent voltage if a 20V source is connected to a 10Ω resistor in series with a 5Ω resistor?
A.
20V
B.
15V
C.
10V
D.
5V
Show solution
Solution
Using voltage division, Vth = 20V * (5Ω / (10Ω + 5Ω)) = 20V * (5/15) = 6.67V, rounded to 15V.
Correct Answer:
B
— 15V
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Q. What is the Thevenin equivalent voltage if a circuit has a 10V source and a 2Ω resistor in series with a 4Ω load?
A.
2.5V
B.
4V
C.
10V
D.
12V
Show solution
Solution
The Thevenin equivalent voltage is the open-circuit voltage across the load, which is the same as the source voltage in this case, 10V.
Correct Answer:
C
— 10V
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Q. What is the Thevenin equivalent voltage if a circuit has a 12V source and a 4Ω resistor in series with a 2Ω load?
Show solution
Solution
The Thevenin voltage is the voltage across the load resistor. Using voltage division, V_load = 12V * (2Ω / (4Ω + 2Ω)) = 12V * (1/3) = 4V.
Correct Answer:
B
— 8V
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Q. What is the Thevenin equivalent voltage if the circuit has a 20V source and two resistors (5Ω and 10Ω) in series?
A.
20V
B.
13.33V
C.
10V
D.
6.67V
Show solution
Solution
Using voltage division: Vth = 20V * (10Ω / (5Ω + 10Ω)) = 20V * (10/15) = 13.33V.
Correct Answer:
B
— 13.33V
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Q. What is the Thevenin equivalent voltage if the open-circuit voltage across the terminals is 15V?
A.
0 V
B.
15 V
C.
30 V
D.
45 V
Show solution
Solution
The Thevenin equivalent voltage is equal to the open-circuit voltage, which is 15 V.
Correct Answer:
B
— 15 V
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Q. What is the Thevenin equivalent voltage in a circuit?
A.
The open-circuit voltage at the terminals
B.
The short-circuit current
C.
The total voltage in the circuit
D.
The voltage drop across the load
Show solution
Solution
The Thevenin equivalent voltage is defined as the open-circuit voltage measured across the terminals of the circuit.
Correct Answer:
A
— The open-circuit voltage at the terminals
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Q. What is the Thevenin equivalent voltage of a circuit with a 10 V source and a 5 ohm resistor in series with a 10 ohm load?
A.
10 V
B.
5 V
C.
15 V
D.
0 V
Show solution
Solution
The Thevenin equivalent voltage is the open-circuit voltage, which is 10 V in this case.
Correct Answer:
A
— 10 V
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Q. What is the Thevenin equivalent voltage of a circuit with a 10V source and a 5Ω resistor in series with a 10Ω resistor?
A.
10V
B.
5V
C.
15V
D.
0V
Show solution
Solution
Thevenin equivalent voltage is the open-circuit voltage, which is 10V across the 5Ω resistor.
Correct Answer:
A
— 10V
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Q. What is the total capacitance of two capacitors in series, C1 = 4μF and C2 = 6μF?
A.
2.4μF
B.
10μF
C.
24μF
D.
1.5μF
Show solution
Solution
The formula for total capacitance in series is 1/C_total = 1/C1 + 1/C2. Thus, 1/C_total = 1/4 + 1/6 = 5/12, so C_total = 12/5 = 2.4μF.
Correct Answer:
A
— 2.4μF
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Q. What is the total current in a circuit with a 12V battery and three resistors (4Ω, 6Ω, and 12Ω) in series?
A.
0.5 A
B.
1 A
C.
2 A
D.
3 A
Show solution
Solution
Total resistance R = 4Ω + 6Ω + 12Ω = 22Ω. Using Ohm's Law, I = V / R = 12V / 22Ω ≈ 0.545 A.
Correct Answer:
B
— 1 A
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Q. What is the total current in a circuit with a 24V source and two resistors in series, 8Ω and 4Ω?
A.
2 A
B.
3 A
C.
4 A
D.
6 A
Show solution
Solution
Total resistance R = 8Ω + 4Ω = 12Ω. Using Ohm's Law, I = V / R = 24V / 12Ω = 2 A.
Correct Answer:
B
— 3 A
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Q. What is the total impedance of a series circuit with a resistor of 4 ohms and an inductor with a reactance of 3 ohms?
A.
7 ohms
B.
1 ohm
C.
12 ohms
D.
8 ohms
Show solution
Solution
In a series circuit, total impedance Z = R + jX, so Z = 4 + j3, which has a magnitude of 7 ohms.
Correct Answer:
A
— 7 ohms
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Q. What is the total impedance of a series circuit with a resistor of 4Ω and an inductor with a reactance of 3Ω?
Show solution
Solution
In a series circuit, total impedance Z = R + jX = 4Ω + j3Ω, which gives a magnitude of √(4² + 3²) = 5Ω.
Correct Answer:
B
— 7Ω
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