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. According to Kirchhoff's Current Law (KCL), the sum of currents entering a junction is equal to what?
A.
The sum of currents leaving the junction
B.
The total voltage at the junction
C.
The total resistance at the junction
D.
Zero
Show solution
Solution
KCL states that the total current entering a junction must equal the total current leaving that junction, ensuring conservation of charge.
Correct Answer:
A
— The sum of currents leaving the junction
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Q. According to Kirchhoff's Current Law (KCL), what can be said about the current entering a junction?
A.
It must equal the current leaving the junction.
B.
It can be greater than the current leaving.
C.
It can be less than the current leaving.
D.
It has no relation to the current leaving.
Show solution
Solution
KCL states that the total current entering a junction must equal the total current leaving the junction.
Correct Answer:
A
— It must equal the current leaving the junction.
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Q. According to Kirchhoff's Current Law (KCL), what can be said about the currents entering and leaving a junction?
A.
They are always equal
B.
They can be different
C.
They depend on voltage
D.
They are always zero
Show solution
Solution
KCL states that the total current entering a junction must equal the total current leaving that junction.
Correct Answer:
A
— They are always equal
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Q. According to Kirchhoff's Current Law (KCL), what must be true at a junction in an electrical circuit?
A.
The sum of voltages is zero
B.
The sum of currents entering equals the sum of currents leaving
C.
Power is conserved
D.
Resistance is constant
Show solution
Solution
KCL states that the total current entering a junction must equal the total current leaving that junction.
Correct Answer:
B
— The sum of currents entering equals the sum of currents leaving
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Q. According to Kirchhoff's Current Law (KCL), what must be true at a junction?
A.
The sum of voltages is zero
B.
The sum of currents entering equals the sum of currents leaving
C.
The total power is conserved
D.
The total resistance is constant
Show solution
Solution
KCL states that the sum of currents entering a junction must equal the sum of currents leaving that junction.
Correct Answer:
B
— The sum of currents entering equals the sum of currents leaving
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Q. According to Kirchhoff's Current Law (KCL), what must be true at any junction in a circuit?
A.
The sum of voltages is zero
B.
The sum of currents entering equals the sum of currents leaving
C.
Power is conserved
D.
Current is constant throughout the circuit
Show solution
Solution
KCL states that the sum of currents entering a junction must equal the sum of currents leaving the junction.
Correct Answer:
B
— The sum of currents entering equals the sum of currents leaving
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Q. According to Kirchhoff's Current Law (KCL), what must be true at any junction in an electrical circuit?
A.
The sum of currents entering equals the sum of currents leaving
B.
The voltage is constant
C.
The total resistance is zero
D.
Power is conserved
Show solution
Solution
KCL states that the total current entering a junction must equal the total current leaving that junction.
Correct Answer:
A
— The sum of currents entering equals the sum of currents leaving
Learn More →
Q. According to Kirchhoff's Voltage Law (KVL), the sum of the voltages around a closed loop is equal to what?
A.
Zero
B.
The total current
C.
The total resistance
D.
The power consumed
Show solution
Solution
KVL states that the sum of the electrical potential differences (voltages) around any closed network is zero.
Correct Answer:
A
— Zero
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Q. How do you calculate the total power in a resistive AC circuit?
A.
P = V^2 / R
B.
P = I^2 * R
C.
P = V * I * cos(φ)
D.
P = R * I
Show solution
Solution
In a resistive AC circuit, the total power (P) can be calculated using the formula P = V * I * cos(φ), where φ is the phase angle between voltage and current.
Correct Answer:
C
— P = V * I * cos(φ)
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Q. How do you calculate the total power in a three-phase AC system?
A.
P = √3 * V * I
B.
P = V * I
C.
P = 3 * V * I
D.
P = V^2 / R
Show solution
Solution
The total power in a balanced three-phase AC system can be calculated using the formula P = √3 * V * I, where V is the line voltage and I is the line current.
Correct Answer:
A
— P = √3 * V * I
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Q. If a capacitor has a capacitance of 10μF and is charged to 5V, what is the stored energy?
A.
0.125 mJ
B.
0.25 mJ
C.
0.5 mJ
D.
1 mJ
Show solution
Solution
Energy stored in a capacitor is given by E = 0.5 * C * V^2 = 0.5 * 10μF * (5V)^2 = 0.125 mJ.
Correct Answer:
A
— 0.125 mJ
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Q. If a circuit has a 15V source and a total resistance of 3Ω, what is the total power consumed in the circuit?
A.
45W
B.
75W
C.
25W
D.
15W
Show solution
Solution
Power P = V^2 / R = 15^2 / 3 = 225 / 3 = 75W.
Correct Answer:
B
— 75W
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Q. If a circuit has a Norton equivalent current of 2A and a Norton equivalent resistance of 4Ω, what is the Thevenin equivalent voltage?
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Solution
Vth = In * Rn = 2A * 4Ω = 8V.
Correct Answer:
C
— 8V
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Q. If a circuit has a Norton equivalent current of 2A and a Norton equivalent resistance of 5Ω, what is the equivalent voltage?
A.
5V
B.
10V
C.
15V
D.
20V
Show solution
Solution
V = I * R = 2A * 5Ω = 10V.
Correct Answer:
B
— 10V
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Q. If a circuit has a Norton equivalent current of 2A and a Norton resistance of 3Ω, what is the Thevenin equivalent resistance?
Show solution
Solution
Thevenin resistance is equal to Norton resistance: Rth = Rn = 3Ω.
Correct Answer:
A
— 3Ω
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Q. If a circuit has a Norton equivalent current of 3A and a Norton equivalent resistance of 4Ω, what is the equivalent voltage?
A.
12V
B.
7V
C.
3V
D.
1.5V
Show solution
Solution
Using Ohm's Law, V = I * R = 3A * 4Ω = 12V.
Correct Answer:
A
— 12V
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Q. If a circuit has a Norton equivalent current of 3A and a Norton equivalent resistance of 2Ω, what is the equivalent voltage?
A.
6V
B.
1.5V
C.
3V
D.
0.5V
Show solution
Solution
The equivalent voltage (V) can be calculated using V = I * R. Therefore, V = 3A * 2Ω = 6V.
Correct Answer:
A
— 6V
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Q. If a circuit has a Norton equivalent current of 5A and a Norton equivalent resistance of 2Ω, what is the equivalent voltage across the terminals?
A.
10V
B.
5V
C.
2.5V
D.
0V
Show solution
Solution
Using Ohm's law: V = I * R = 5A * 2Ω = 10V.
Correct Answer:
A
— 10V
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Q. If a circuit has a Norton equivalent current of 5A and a Norton equivalent resistance of 2Ω, what is the voltage across the terminals?
A.
10V
B.
5V
C.
2.5V
D.
0V
Show solution
Solution
Using Ohm's law, V = I * R = 5A * 2Ω = 10V.
Correct Answer:
A
— 10V
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Q. If a circuit has a Norton equivalent current of 5A and a Norton equivalent resistance of 2Ω, what is the equivalent voltage?
Show solution
Solution
Using Ohm's Law, V = I * R = 5A * 2Ω = 10V.
Correct Answer:
C
— 10V
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Q. If a circuit has a Norton equivalent of 2A and a load resistance of 8Ω, what is the power delivered to the load?
A.
0.5W
B.
1W
C.
2W
D.
4W
Show solution
Solution
Power (P) = I^2 * R = (2A)^2 * 8Ω = 4 * 8 = 32W.
Correct Answer:
C
— 2W
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Q. If a circuit has a Thevenin equivalent of 15V and a load resistance of 5Ω, what is the load current?
A.
3A
B.
2A
C.
1A
D.
0.5A
Show solution
Solution
Using Ohm's law: I = V/R = 15V / 5Ω = 3A.
Correct Answer:
B
— 2A
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Q. If a circuit has a Thevenin equivalent of 5V and 10Ω, what is the current through a load resistor of 5Ω connected across the terminals?
A.
1A
B.
0.5A
C.
2A
D.
0.25A
Show solution
Solution
Using Ohm's law, the current through the load can be calculated as I = Vth / (Rth + Rload) = 5V / (10Ω + 5Ω) = 5V / 15Ω = 0.33A.
Correct Answer:
B
— 0.5A
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Q. If a circuit has a Thevenin equivalent of 5V and a load resistance of 10Ω, what is the load current?
A.
0.5A
B.
1A
C.
2A
D.
5A
Show solution
Solution
Using Ohm's law, I = V / R = 5V / 10Ω = 0.5A.
Correct Answer:
B
— 1A
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Q. If a circuit has a Thevenin equivalent resistance of 5Ω and a load of 10Ω, what is the current through the load?
A.
0.8A
B.
1A
C.
1.2A
D.
1.5A
Show solution
Solution
Using the formula I = Vth / (Rth + Rload), where Vth = 10V, I = 10V / (5Ω + 10Ω) = 10V / 15Ω = 0.67A.
Correct Answer:
B
— 1A
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Q. If a circuit has a total impedance of 4Ω and a current of 3A, what is the voltage across the circuit?
A.
12V
B.
10V
C.
15V
D.
8V
Show solution
Solution
Using Ohm's law, V = I * Z = 3A * 4Ω = 12V.
Correct Answer:
A
— 12V
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Q. If a circuit has a total impedance of 6Ω and a current of 2A, what is the voltage across the circuit?
A.
12V
B.
10V
C.
8V
D.
6V
Show solution
Solution
Using Ohm's Law, V = I * Z = 2A * 6Ω = 12V.
Correct Answer:
A
— 12V
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Q. If a circuit has a total voltage of 120V and a total current of 10A, what is the total power in the circuit?
A.
1200W
B.
100W
C.
10W
D.
120W
Show solution
Solution
Power P = V * I = 120V * 10A = 1200W.
Correct Answer:
A
— 1200W
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Q. If a circuit has a voltage of 12V and a resistance of 4Ω, what is the current flowing through the circuit?
A.
3A
B.
4A
C.
12A
D.
48A
Show solution
Solution
Using Ohm's Law (I = V / R), the current is I = 12V / 4Ω = 3A.
Correct Answer:
A
— 3A
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Q. If the total power in a circuit is 100W and the power factor is 0.8, what is the apparent power?
A.
80VA
B.
100VA
C.
125VA
D.
200VA
Show solution
Solution
Apparent power (S) is calculated using S = P / power factor. Here, S = 100W / 0.8 = 125VA.
Correct Answer:
C
— 125VA
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