What is the difference between Active and Passive components?

Active components (e.g., Transistors, Diodes) require an external source to operate and can inject power. Passive components (e.g., Resistors, Capacitors) do not require an external source and cannot amplify signals.

Why is Silicon diode preferred over Germanium?

Silicon is preferred because it has a higher Peak Inverse Voltage (PIV) rating, better thermal stability, and is more abundant/cheaper than Germanium, despite having a higher voltage drop (0.7V vs 0.3V).

What is the Nyquist Criteria for Sampling?

The Nyquist criteria states that to prevent data loss and aliasing, the sampling rate (fs) must be at least twice the maximum frequency (fmax) of the analog signal (fs >= 2fmax).

What is a Universal Logic Gate?

A universal gate is a logic gate that can be used to implement any Boolean function without needing any other type of gate. The two universal gates are NAND and NOR.

Top 65+ Basic Electronics Engineering Interview Questions [2025]

65+ Basic Electronics Engineering Interview Questions & Answers

The Ultimate Guide for 2025 | Circuit Theorems, Semiconductors, Communication & Digital Logic

Electronics Engineering, like any other engineering job, has many technical questions. To shine better at an electronics engineering interview, you need to have a strong grip over the technical questions. You need to keep yourself updated with electronics engineering interview questions to outperform other candidates. You do not want someone who has no knowledge about technical questions to outperform you in the electronics engineering interview.

⚡ Related Resource: For broader engineering topics, check out our guide on 60+ Electrical Engineering Interview Questions & Answers.

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Here are some of the most asked basic Electronics Engineering interview questions.

Part 1: Fundamentals of Electronics & Components

1. What is Electronics Engineering?

💡 Direct Answer:
Electronics engineering is a field of engineering which deals with the utilization of active and passive electronic components to design a variety of different analog and digital circuits, devices, and systems.

These devices are implemented in logic circuits, communication systems, robotics, microprocessors, and Artificial intelligence to perform useful tasks efficiently and for the betterment of human beings.

It usually deals with low current voltage (compared to Electrical Engineering) specifically between -48V to 48V. For larger scale voltage systems, we recommend reviewing our electrical system assessment procedures.

2. What are Active and Passive components?

💡 Direct Answer:
Active components require an external source to operate and can control electron flow (e.g., Transistors). Passive components do not require an external source and cannot amplify signals (e.g., Resistors).

Active Components: Components which require an external source for its full operation such as Diode, Transistor, Thyristor etc.
Passive Components: Components which do not need any external source for its function. Example of passive components is resistor, capacitor & Inductor.

3. What is a Resistor?

💡 Direct Answer:
A passive component that opposes current flow, creating a voltage drop calculated by Ohm’s Law: $V = IR$ .

A resistor is an electronic component with two terminals, which resist or oppose the electrical current in its path. It also develops a voltage drop across its terminals, which depends on the current flowing through it.

4. What is a Capacitor?

💡 Direct Answer:
A device that stores energy in an electric field. The stored charge is $Q = CV$ , where C is capacitance in Farads.

A capacitor is a two-terminal electronic component, which stores potential energy in the form of charge. The property or ability of the capacitor to store charge is called capacitance and it is measured in Farad.

5. What is an Inductor?

💡 Direct Answer:
A component that opposes changes in current flow, storing energy in a magnetic field. Voltage induced is $V = L(di/dt)$ .

An inductor is an electronic device, which resists the change in electrical current passing through it. It stores energy in the form of the magnetic field when the current pass through it.

6. What is Practical & Ideal Voltage Source?

💡 Direct Answer:
Ideal: Zero internal resistance, constant voltage regardless of load. Practical: Has internal resistance, causing voltage drop as load increases.

A voltage source having some internal resistance is called a practical voltage source. Due to this resistance, there is a voltage drop. The supply voltage of the practical voltage source decreases with an increase in the current.

If the internal resistance of a voltage source becomes zero the source is said to be an ideal voltage source. And its voltage does not decrease with the increase in current.

7. What is Practical & Ideal Current Source?

💡 Direct Answer:
Ideal: Infinite internal resistance, constant current. Practical: Large finite resistance, current decreases slightly as voltage increases.

The ideal current source has infinite internal resistance. Its current does not depend on its supply voltage. A practical current source has a large internal resistance. Its supply current decreases with the increase in its supply voltage. Proper monitoring of these sources is vital in energy monitoring solutions.

Part 2: Circuit Theorems & Semiconductor Devices

8. What is Norton’s Theorem?

💡 Direct Answer:
Any linear bilateral network can be replaced by an equivalent circuit consisting of a current source ( $I_N$ ) in parallel with a resistor ( $R_N$ ).

Any combination of batteries and resistances in a linear circuit is equivalent to and can be represented by an ideal current source and a resistor in parallel.

9. What is Thevenin’s Theorem?

💡 Direct Answer:
Any linear bilateral network can be replaced by an equivalent circuit consisting of a voltage source ( $V_{TH}$ ) in series with a resistor ( $R_{TH}$ ).

Any combination of batteries and resistance in a linear circuit can be represented by a signal voltage source and a resistor in series.

10. Transistors and Switching Operation

💡 Direct Answer:
A transistor acts as a switch when operated in Saturation (Closed Switch/ON) and Cutoff (Open Switch/OFF) regions.

A transistor is a three-terminal semiconductor device. It is can be used for amplifying or switching an electrical signal.

How does the Transistor act as a Switch?

In the active region, the transistor acts as an amplifier.
In the saturation region, the transistor acts as a closed switch.
In the cutoff region, the transistor acts as an open switch.

So to use a transistor as a switch, it needs to be operated in the saturation & cutoff region.

11. What is meant by Clipper and Clamper?

💡 Direct Answer:
Clipper: Limits the voltage amplitude (waveform shaping). Clamper: Shifts the DC level of the signal without changing its shape.

A clipper is a circuit that clips or cutoff voltage above or below a certain specified level. Positive clipper cuts off a portion of positive half of a signal while negative clipper cuts off from the negative half.

A clamper is a circuit that adds voltage in the positive or negative half of the signal to a specified peak voltage. A clamper moves the whole signal up and down to reach the specified peak voltage.

12. What is SCR?

💡 Direct Answer:
Silicon Controlled Rectifier (SCR) is a unidirectional 4-layer solid-state device that controls current flow using a Gate pulse.

Silicon controlled rectifier or thyristor is unidirectional semiconductor device but unlike diode, it has three terminals Anode, Cathode & Gate. The SCR can be switched on & off using the gate input. SCRs are fundamental in controlling high power in low voltage electrical cabinet maintenance.

13. Diode Fundamentals: Silicon vs Germanium

💡 Direct Answer:
Silicon (0.7V drop) is preferred over Germanium (0.3V drop) due to higher thermal stability, higher Peak Inverse Voltage (PIV), and abundance.

A diode is a unidirectional semiconductor device with two terminals called Anode & Cathode. A diode can allow current in only one direction which is known as forward bias.

Difference between Silicon and Germanium Diode & why is Silicon diode preferred?

The voltage drop of a silicon diode is 0.7v and that of germanium diode is 0.3v.
Silicon crystals are more resistant to heat than germanium. Silicon diode has a high voltage rating than the germanium diode.
Silicon diodes are more preferable because silicon is available in abundant compared to germanium.

14. What is the main difference between BJT and FET?

💡 Direct Answer:
BJT: Current-controlled, Bipolar (Electrons & Holes), Low Input Impedance.
FET: Voltage-controlled, Unipolar (Majority carriers only), High Input Impedance.

BJT stand for bipolar junction transistor and FET is the acronym for Field Effect Transistor.
BJT is bipolar that is there is a flow of both minority and majority charge carriers, while FET is unipolar that is there is a flow of only majority carriers.
BJT is controlled using the input current (base current) while FET is controlled using the input voltage (Gate voltage).
The input impedance of FET is much higher compared to BJT.
The three terminals of BJT is emitter, base & collector while FET is drain, gate & source.

15. Operational Amplifier (Op-Amp) Basics

💡 Direct Answer:
An Op-Amp is a high-gain voltage amplifier. It has Infinite Input Impedance (draws negligible current) and Zero Output Impedance (ideal).

Operational amplifier often known as op-amp is an active voltage amplifying component. It can amplify voltage based on the difference of voltage between its two inputs.

What is Inverting and Non-inverting Amplifier?

When the input voltage signal is applied to a non-inverting terminal (+ve terminal) of the Op-amp, the op-amp is said to be in a non-inverting configuration. Its gain is positive i.e. its output signal is in-phase with the input signal.

In inverting op-amp configuration, the input signal is applied to the inverting terminal (-ve terminal) of an op-amp. The gain of inverting op-amp is negative and the output signal is 180 degree out of phase with respect to the input signal.

Part 3: Communication Systems & Signal Processing

16. What is Communication?

The transfer of information from one place to another place using some sort of medium is called Communication. The information could be in any form such as a sound or visual or electrical signal etc.

17. Baseband vs Passband Signal

💡 Direct Answer:
Baseband: Low frequency (0 to 10kHz), requires wire/fiber (cannot be transmitted via antenna).
Passband: High frequency (>100kHz), modulated signal suitable for wireless antenna transmission.

A signal consisting of significantly lower frequency (up to 10 kHz) is known as a baseband signal. Example of the baseband signal is voice (300Hz to 3.5 kHz), audio (20 Hz to 20 kHz) and a video signal (0Hz to 4.5 MHz). The baseband signal cannot be transmitted directly through the antenna. They are transmitted using copper wire or fiber optics etc.

A signal consisting of significantly higher frequencies (Higher than 100 kHz) is known as Passband or BandPass signal. Bandpass signal does not contain any frequency lower than 100 kHz. Bandpass signal can be directly transmitted through the antenna.

18. What is Modulation and Why is it Needed?

💡 Direct Answer:
Modulation varies the carrier signal properties (Amplitude, Frequency, Phase) according to the message signal. It reduces Antenna Height ( $h = \lambda/4$ ) and allows Multiplexing.

The process in which one of the characteristic parameter (amplitude, frequency, phase) of the carrier signal varies linearly with respect to message signal’s amplitude is called modulation.

Why do we need Modulation?

Modulation converts a baseband signal into a passband signal making it suitable for long distance communication using an antenna.
Antenna size also depends on the frequency of the transmitting signal, so the modulation allows us to use a small size antenna.
Using Modulation we can assign different frequencies to different signals which allow us to send multiple signals using the same medium without interference.

19. Modulation Types & AM vs FM

What is Demodulation? The demodulation is a process of extracting the information or message signal from the received or modulated signal.

What are the Types of Modulation?

Two main types of modulation are Analog modulation and Digital modulation.

Analog modulation:
- Amplitude modulation (AM): DSB-FC, DSB-SC, SSB-SC, SSB-FC, VSB
- Frequency modulation (FM): NBFM, WBFM
- Phase modulation (PM)
Digital modulation:
- Digital Amplitude modulation: ASK, PAM, QAM
- Digital phase modulation: PSK, DPSK, OPSK
- Digital Frequency modulation: FSK
- Continuous phase modulation: GMSK, MSK, CPFSK
- Trellis-coded modulation: PSK, QAM

What is the difference between AM and FM Modulation?

AM signals can be affected by noise as the information lies in the amplitude of the signal, while FM is immune to noise because the information lies in the frequency of the signal. The design of Transmitter and receiver for AM is very simple except for some cases like SSB. While in FM, the transmitter and receiver have a complex design. AM signal can travel long distances as compared to FM signals. FM signal’s transmission consume more power as compared to AM signal’s transmission. AM signal frequency ranges in KHz while FM signal frequency ranges in MHz.

20. What is a Repeater in Telecommunication?

💡 Direct Answer:
A device that receives a weak signal, regenerates/amplifies it, and retransmits it to extend transmission distance.

As we know that a transmitted signal loses its power when it travels long distances. To retain and maintain its full power, the signal is boosted through a device known as a repeater for long distance communication. Usually, a repeater retransmits the identical signal but it may change the medium or frequency of the signal according to the need.

21. Analog vs Digital vs Discrete Signals

Analog signal: Continuous time and continuous amplitude.
Digital signal: Discrete time and discrete amplitude (binary 0 and 1).
Discrete signal: Discrete time but continuous amplitude (can have any value at specific time intervals).

22. Sampling, Nyquist Criteria & Aliasing

💡 Direct Answer:
Nyquist Criteria: Sampling rate ( $f_s$ ) must be $\geq 2f_{max}$ .
Aliasing: Distortion occurring when $f_s < 2f_{max}$ , causing high-frequency signals to look like low-frequency noise.

Sampling is a process of converting a continuous time signal into a discrete time signal but not a digital signal.

Suppose the maximum frequency of the analog signal is $f_{max}$ then the Nyquist criteria suggest that the sampling rate for this analog signal must be $2f_{max}$ or greater.

Aliasing is a signal effect related to sampling. When a signal is sampled at a sampling rate less than the required rate, the signal becomes indistinguishable from other signals and after reconstruction, the signal does not look anything like the original signal. This effect is called Aliasing.

23. Filters: Types and Cutoff Frequency

💡 Direct Answer:
Cutoff Frequency: The point at -3dB (Half Power) where the passband meets the stopband.

A Filter is an electronic circuit that removes specific or unwanted frequency components from a signal. In power systems, managing unwanted frequencies is crucial; for more on this, see our harmonic filtering solutions.

The types of filters are: Low pass filter, Bandpass filter, Band stop or band reject filter, High pass filter, Notch filter.

What is Passband and Stop band? The passband is the range of frequencies that can be passed through the filter without any attenuation. The stopband is the range of frequencies that are attenuated and cannot be passed through the filter.

What is the difference between the Notch and Bandstop filter? Band stop filter rejects a wide range of band while notch filter rejects a very narrow band. The notch filter is used for suppressing powerful laser beams.

Part 4: Digital Logic & Systems

24. Logic Gates: Basic, Derived & Universal

💡 Direct Answer:
Universal Gates (NAND, NOR) can implement any boolean function without using other gate types.

A digital logic gate is an electronic device which implements the Boolean function. The boolean function performs a logical operation on one or more than one binary numbers.

Basic Logic Gates: NOT, AND, OR.
Derived Logic Gates: NAND, NOR, XOR, XNOR (made from basic gates).
Universal Logic Gates: NAND & NOR.

25. What is Positive Logic and Negative Logic?

In digital logic, a Specific level of voltage is represented by binary numbers i.e.1 or 0 in other words, True or False respectively.

In positive logic, the High-level voltage is represented by 1 or True & the low-level voltage is represented by 0 or False.
In negative logic, the High-level voltage is represented by 0 or False & the low-level voltage is represented by 1 or True.

26. Latches vs Flip-Flops & Triggering

💡 Direct Answer:
Latches: Level-Triggered (responds to enable input state).
Flip-Flops: Edge-Triggered (responds to clock signal transition).

Latch and flip-flop are memory devices with two stable states. They are used for storing data (states) in sequential logic. The states are controlled using one or more than one control signals. It can store one bit of data.

What is a Level trigger and Edge trigger?

Level trigger: Device changes state based on the level (stable 1 or 0) of the control signal.
Edge trigger: Device changes state based on the edge (rising or falling) of the clock signal.

27. What is Combinational and Sequential logic?

Combinational logic does not have a memory that is its current output depends only on the current input. While sequential logic has a memory and its current output depends on the previous output and current input.

28. Ripple Carry Adder vs Carry Look Ahead Adder

💡 Direct Answer:
Ripple Carry: Slow, delay accumulates as carry ripples through stages.
Carry Look Ahead (CLA): Fast, determines carry bits simultaneously using extra logic.

These two Digital binary adders are differentiated based on the carry determining technique. In ripple carry adder, the carry bits ripple through each individual adder while in a carry-look-ahead adder, the carry bit is determined separately using a CLA (Carry look ahead) block. CLA adder operates much faster than ripple adder as it bypasses many stages. These logical concepts are foundational to modern computing and IoT (Internet of Things) technologies.

Part 5: Transformers & Power Electronics

29. What is a Transformer?

💡 Direct Answer:
A static device that transfers energy between circuits via electromagnetic induction, changing voltage/current levels while keeping frequency constant.

A transformer is a static electrical device which transfers electrical energy from one circuit to another circuit without any physical connection instead it uses the principles of electromagnetic induction. A transformer either increase or decrease the input voltage & current.

[Image of electrical transformer diagram]

For industrial applications, maintaining these devices is critical. We recommend regular transformer maintenance and transformer oil filtration services to ensure longevity.

30. What is an Oscillator?

An oscillator is an electronic circuit which generates a periodic AC signal from a DC source. An oscillator has no input. The output of oscillator can be sinusoidal or Square or a triangle wave.

31. Comparison & Differences

When preparing for your interview, ensure you also understand the detailed differences between components. For example, understanding the socket vs outlet vs receptacle difference is basic but essential knowledge.

Conclusion

Some of the electronics engineering interview questions may be more casual like “why you choose this field?” etc. but we are covering more technical question. These are some of the basic electronic engineering interview questions. If you think there are some questions related to electronics engineering interview that may have been asked or need to be added, please, feel free to contact us or use the comment box below to include any questions you like or interviewer asked in an interview for electronics engineering related job.

Stay tuned for more updates and questions related to electronics engineering interview as we will add even more. For advanced study materials, check out our list of Top 7 Essential Books for Electricians 2025.