Electronics MCQ & Objective Questions
Electronics is a crucial subject for students preparing for school exams and competitive tests in India. Mastering this topic not only enhances your understanding of fundamental concepts but also boosts your confidence in tackling objective questions. Practicing MCQs and important questions in Electronics helps you identify your strengths and weaknesses, ensuring effective exam preparation.
What You Will Practise Here
Basic concepts of current, voltage, and resistance
Understanding of Ohm's Law and its applications
Key components such as resistors, capacitors, and transistors
Fundamentals of circuit diagrams and analysis
Principles of alternating current (AC) and direct current (DC)
Signal processing and its applications in real-world scenarios
Important formulas related to power, energy, and circuit calculations
Exam Relevance
Electronics is a significant topic in various examinations, including CBSE, State Boards, NEET, and JEE. Students can expect questions that assess their understanding of basic concepts, circuit analysis, and application of theories. Common question patterns include multiple-choice questions that test both theoretical knowledge and practical application, making it essential to practice thoroughly.
Common Mistakes Students Make
Confusing the concepts of AC and DC, leading to incorrect answers.
Overlooking the significance of units in calculations, resulting in errors.
Misinterpreting circuit diagrams, which can lead to faulty analysis.
Neglecting to apply Ohm's Law correctly in problem-solving.
FAQs
Question: What are the key topics to focus on in Electronics for exams?Answer: Focus on circuit analysis, basic components, Ohm's Law, and signal processing.
Question: How can I improve my performance in Electronics MCQs?Answer: Regular practice of MCQs and understanding the underlying concepts will significantly enhance your performance.
Don't wait any longer! Dive into our Electronics MCQs and practice questions to solidify your understanding and excel in your exams. Your success starts with the right preparation!
Q. In a series RLC circuit, what happens when the damping ratio is less than 1?
A.
The circuit is overdamped
B.
The circuit is critically damped
C.
The circuit is underdamped
D.
The circuit is unstable
Show solution
Solution
When the damping ratio (ζ) is less than 1 in a series RLC circuit, the circuit is considered underdamped, leading to oscillatory behavior.
Correct Answer:
C
— The circuit is underdamped
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Q. In a series-parallel circuit, how does a BJT operate when used as a switch?
A.
In cutoff mode, it conducts current
B.
In saturation mode, it blocks current
C.
In saturation mode, it conducts current
D.
In active mode, it blocks current
Show solution
Solution
A BJT operates in saturation mode to allow maximum current flow, effectively acting as a closed switch.
Correct Answer:
C
— In saturation mode, it conducts current
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Q. In a series-parallel circuit, what is the effect of connecting multiple diodes in parallel?
A.
Increases total voltage
B.
Increases total current capacity
C.
Decreases total current capacity
D.
Has no effect on current
Show solution
Solution
Connecting multiple diodes in parallel increases the total current capacity of the circuit.
Correct Answer:
B
— Increases total current capacity
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Q. In a small-signal model of a parallel circuit, how are the components represented?
A.
As linear elements only
B.
As nonlinear elements only
C.
As a combination of linear and nonlinear elements
D.
As ideal voltage sources
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Solution
In a small-signal model, components are typically represented as linear elements to simplify analysis around a bias point.
Correct Answer:
A
— As linear elements only
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Q. In a small-signal model of a parallel circuit, the output voltage is:
A.
The same as the input voltage
B.
Dependent on the load
C.
Always zero
D.
Equal to the sum of the input voltages
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Solution
In a small-signal model, the output voltage is dependent on the load and the configuration of the circuit.
Correct Answer:
B
— Dependent on the load
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Q. In a small-signal model, how is a capacitor typically represented?
A.
As an open circuit
B.
As a short circuit
C.
As a resistor
D.
As a dependent source
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Solution
In small-signal models, capacitors are often represented as short circuits at high frequencies.
Correct Answer:
B
— As a short circuit
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Q. In a small-signal model, how is the output voltage related to the input voltage in an RL circuit?
A.
Output voltage is always greater than input voltage
B.
Output voltage is always less than input voltage
C.
Output voltage can be greater or less depending on the circuit configuration
D.
Output voltage is independent of input voltage
Show solution
Solution
In a small-signal model, the output voltage can vary based on the circuit configuration and the values of R and L.
Correct Answer:
C
— Output voltage can be greater or less depending on the circuit configuration
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Q. In a small-signal model, what does the output voltage of an op-amp depend on?
A.
Input voltage and feedback
B.
Only input voltage
C.
Only feedback
D.
Power supply voltage
Show solution
Solution
In a small-signal model, the output voltage of an op-amp depends on both the input voltage and the feedback configuration.
Correct Answer:
A
— Input voltage and feedback
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Q. In a small-signal model, what does the transconductance (gm) of a BJT represent?
A.
The input resistance
B.
The output resistance
C.
The change in output current per change in input voltage
D.
The change in input current per change in output voltage
Show solution
Solution
Transconductance (gm) indicates how much the output current changes in response to a change in input voltage.
Correct Answer:
C
— The change in output current per change in input voltage
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Q. In a small-signal model, what does the transconductance (gm) represent?
A.
The change in output voltage per change in input current
B.
The change in output current per change in input voltage
C.
The change in input voltage per change in output current
D.
The change in input current per change in output voltage
Show solution
Solution
Transconductance (gm) represents the change in output current per change in input voltage in a small-signal model.
Correct Answer:
B
— The change in output current per change in input voltage
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Q. In a step-up transformer, the number of turns in the primary coil is:
A.
Greater than the secondary coil
B.
Less than the secondary coil
C.
Equal to the secondary coil
D.
None of the above
Show solution
Solution
In a step-up transformer, the primary coil has fewer turns than the secondary coil.
Correct Answer:
B
— Less than the secondary coil
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Q. In a summing amplifier configuration, what is the role of the feedback resistor?
A.
To set the gain of the amplifier
B.
To provide stability
C.
To determine the input impedance
D.
To filter noise
Show solution
Solution
The feedback resistor in a summing amplifier sets the gain of the amplifier for the summed inputs.
Correct Answer:
A
— To set the gain of the amplifier
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Q. In a summing amplifier using an op-amp, what is the output voltage if the inputs are 2V and 3V with equal resistors?
A.
5V
B.
2.5V
C.
1V
D.
0V
Show solution
Solution
In a summing amplifier with equal resistors, the output voltage is the average of the inputs, which is 2.5V.
Correct Answer:
B
— 2.5V
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Q. In a thyristor, what is the role of the gate terminal?
A.
To provide a path for current
B.
To control the turn-on of the device
C.
To dissipate heat
D.
To connect to the load
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Solution
The gate terminal is used to trigger the thyristor into conduction.
Correct Answer:
B
— To control the turn-on of the device
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Q. In a transformer, the turns ratio determines what?
A.
The efficiency of the transformer
B.
The frequency of the output signal
C.
The voltage transformation ratio
D.
The power rating of the transformer
Show solution
Solution
The turns ratio of a transformer determines the voltage transformation ratio.
Correct Answer:
C
— The voltage transformation ratio
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Q. In a transformer, what role does the inductor play?
A.
It converts AC to DC
B.
It stores energy
C.
It transfers energy between circuits
D.
It filters signals
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Solution
In a transformer, the inductor transfers energy between circuits through electromagnetic induction.
Correct Answer:
C
— It transfers energy between circuits
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Q. In an inverting amplifier, if the feedback resistor is 10k Ohm and the input resistor is 1k Ohm, what is the gain?
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Solution
The gain of an inverting amplifier is given by -Rf/Rin, which in this case is -10.
Correct Answer:
A
— -10
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Q. In an op-amp configured as a voltage follower in a series circuit, what is the output voltage relative to the input voltage?
A.
Higher than the input voltage
B.
Lower than the input voltage
C.
Equal to the input voltage
D.
Inverted compared to the input voltage
Show solution
Solution
An op-amp in a voltage follower configuration outputs a voltage that is equal to the input voltage, providing high input impedance and low output impedance.
Correct Answer:
C
— Equal to the input voltage
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Q. In an op-amp configured as a voltage follower in a series circuit, what is the output voltage compared to the input voltage?
A.
Higher than the input voltage
B.
Lower than the input voltage
C.
Equal to the input voltage
D.
Unpredictable
Show solution
Solution
An op-amp in a voltage follower configuration outputs a voltage that is equal to the input voltage.
Correct Answer:
C
— Equal to the input voltage
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Q. In an operational amplifier, what does the term 'common-mode rejection ratio' (CMRR) refer to?
A.
The ability to reject noise
B.
The ability to reject common-mode signals
C.
The ratio of output to input voltage
D.
The gain of the amplifier
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Solution
Common-mode rejection ratio (CMRR) refers to the ability of an operational amplifier to reject common-mode signals.
Correct Answer:
B
— The ability to reject common-mode signals
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Q. In an RC circuit, what does the time constant (τ) represent?
A.
The time taken to charge or discharge the capacitor
B.
The maximum voltage across the capacitor
C.
The resistance of the circuit
D.
The frequency of oscillation
Show solution
Solution
The time constant (τ) in an RC circuit is the time taken for the capacitor to charge to about 63.2% of the maximum voltage.
Correct Answer:
A
— The time taken to charge or discharge the capacitor
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Q. In an RL circuit, what does the time constant represent?
A.
The time to charge the inductor
B.
The time to discharge the inductor
C.
The time to reach 63.2% of final value
D.
The time to reach 100% of final value
Show solution
Solution
In an RL circuit, the time constant (τ) represents the time it takes for the current to reach approximately 63.2% of its final value.
Correct Answer:
C
— The time to reach 63.2% of final value
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Q. In an RLC series circuit, what is the effect of increasing the resistance on the bandwidth?
A.
Bandwidth increases
B.
Bandwidth decreases
C.
Bandwidth remains the same
D.
Bandwidth becomes zero
Show solution
Solution
Increasing the resistance in an RLC series circuit decreases the bandwidth due to increased damping.
Correct Answer:
B
— Bandwidth decreases
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Q. In semiconductor physics, what happens to the current in a parallel diode configuration when the temperature increases?
A.
Current decreases
B.
Current remains constant
C.
Current increases
D.
Current becomes zero
Show solution
Solution
In a parallel diode configuration, as the temperature increases, the current typically increases due to reduced barrier potential.
Correct Answer:
C
— Current increases
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Q. In semiconductor physics, what happens to the resistance of a diode when it is forward-biased in a series circuit?
A.
Resistance increases
B.
Resistance decreases
C.
Resistance remains constant
D.
Resistance becomes infinite
Show solution
Solution
When a diode is forward-biased, its resistance decreases, allowing current to flow easily through the series circuit.
Correct Answer:
B
— Resistance decreases
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Q. In semiconductor physics, what happens to the resistance of a diode when it is forward-biased?
A.
Resistance increases
B.
Resistance decreases
C.
Resistance remains constant
D.
Resistance becomes infinite
Show solution
Solution
When a diode is forward-biased, its resistance decreases, allowing current to flow easily.
Correct Answer:
B
— Resistance decreases
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Q. In semiconductor physics, what is a p-n junction?
A.
A type of transistor
B.
A boundary between p-type and n-type materials
C.
A method of signal modulation
D.
A type of capacitor
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Solution
A p-n junction is the interface between p-type and n-type semiconductor materials, crucial for diode operation.
Correct Answer:
B
— A boundary between p-type and n-type materials
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Q. In semiconductor physics, what is the purpose of doping?
A.
To increase the thermal conductivity
B.
To create p-type or n-type materials
C.
To enhance the mechanical strength
D.
To reduce the energy band gap
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Solution
Doping introduces impurities into a semiconductor to create p-type or n-type materials, enhancing conductivity.
Correct Answer:
B
— To create p-type or n-type materials
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Q. In semiconductor physics, what is the term for the energy gap between the valence band and the conduction band?
A.
Fermi level
B.
Band gap
C.
Conductivity
D.
Doping level
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Solution
The band gap is the energy difference between the valence band and the conduction band in semiconductors.
Correct Answer:
B
— Band gap
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Q. In small-signal analysis, what is the purpose of the small-signal model?
A.
To analyze large signal behavior
B.
To simplify circuit analysis for small variations
C.
To determine thermal characteristics
D.
To calculate power dissipation
Show solution
Solution
The small-signal model is used to simplify circuit analysis for small variations around a bias point.
Correct Answer:
B
— To simplify circuit analysis for small variations
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