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Top 20 Very Basic Electrical Engineering Interview Questions with their Answers


Looks like you have your interview scheduled sometime soon. It is always good to brush up your subject matter skills for your electrical engineering interview questions. When you will open your books, you will get flashbacks of the trauma that you sustained during the four years of studying.

Brushing over basic electrical engineering interview questions can be a tricky task. The book seems to be an endless saga of topics which roots deep into the matter. However, a secret is when you go for an interview, the interviewer is not looking at your rote learning skills. On the contrary, they are assessing your ability to understand the basic concepts. In other words, one must focus on basic knowledge instead of mugging up of the whole book.

And that is exactly what I bring forth with this article. Here, I try to present the top 20 basic electrical engineering interview questions that organisations go for. These questions will not only help you to revise the concepts but also prepare you for the electrical interview.

Basic Electrical Engineering Interview Questions with Answers

Q1. What part of an atom is called a valance?

The outermost shell of the atom is valence.

Q2. Define the concepts of inductance and capacitance.

Capacitor helps in the storage of the total amount of capacitance at the measured voltage. Inductance is the resistance of the coil in changes of electrical current flowing through the system. When a second coil opposes the effect of the charge in the first coil, it leads to mutual inductance.

Q3. What is the effect of placing two positively charged materials placed next to each other?

As positives repel and opposites attract, the two materials will repel and move away from each other.

Q4. Mention the three different types of cables used in transmissions.

Different types of cables that are used in transmission:

  • Low Tension (upto 1000 volts)
  • High Tension (upto 23000 volts)
  • Super Tension (upto 132 kv)

These wires can categorized on the basis of their voltage and thermal capacity.

Q5. Define reverse polarity and the process of fixing it.

Incorrect placement of receptacles leads to Reverse polarity. The simple process to fix this problem is to check the connection of the wire from the outlet or by inspecting the receptacle. When the white wire is connected to the hot side and the black wire is connected to the neutral side, it leads to reverse polarity. Swapping this entanglement will solve reverse polarity.

Q6. Describe the function of the different coloured wires.
function of the different coloured wires
The different types of colours of wires signal the different functions they undertake. Primarily, there are 7 types of colour which have their own coding:

  • Black: The black wire is the main source of power supply in the circuit. Not used for ground wires, these black wires are either in the hot state or live state.
  • Green: This wire connects to the ground terminal. An outlet box contains green wires and it can only be spread within a panel (electrical).
  • Red: Red wire is the second wire, It transmits the live state of the wire. It can be used in different types of interconnections and are present in a circuit of 220 volts. Moreover it can either be connect to another red wire, or to a black wire.
  • White/Gray: Neutral wires depict this color. It helps in carrying out the unbalanced load to the terminal. The terminal is located in the ground. The wire can connect itself to its own types of wires.
  • Blue/Yellow: The wire carry power, therefore they use itself for live wires. common devices does not these wires. One can easily find these wires in devices like fans, lights, etc.

Q7. Differentiate between a generator and alternator.

While both mechanisms work on the same basic principle of converting mechanical energy into electrical engineering, the differences are as follows-

  • Alternator: An alternator uses a rotating stationary armature, which is magnetic, for releasing higher voltage and a stationary magnetic field with an armature that is rotating, for releasing lower voltage.
  • Generator: A generator, on the other hand, uses a revolving conductor rolling onto armatures using brushes and rings, along with a stationary magnetic field to convert Electro-Motive Force (EMF)

Q8. What are the different criteria you will keep in mind while selecting a type of wire?

Wires selection is based on a number of factors ranging from varying wire capacity to the gauge of the different wires. If my demand rests on using larger and heavier products, like those of electrical heaters or furnaces, I will be choosing a smaller gauge of wire, maybe gauge 6, as it has a higher capacity to carry and handle the current. On the other hand, if I have to choose wires for household objects like lamps and lights, which require a low voltage, I will go for wires with higher gauge values, maybe around 12.

Q9. What is the RLC current?

The word RLC is a combination of the three elements of the circuit- Resistor (R), inductor (L) and Current (C), and is an electrical circuit. An RLC circuit is also known as a second-order circuit for its ability to direct voltage or current that is flowing throughout the circuit and the ability of it to be characterised by a differential equation of the second order.

Q10. What are semiconductors?

what are semiconductors

Semiconductors are a combination of properties that belong to both an electrical conductor, such as copper, and an insulator, like sand. There are different types of semiconductors, which are intrinsic and extrinsic semiconductors. Extrinsic semiconductors have a further classification into n-type extrinsic semiconductors and p-type extrinsic semiconductors.

Q11. Define a Zener diode.

A Zener diode is a semiconducting diode, it helps current to flow into the opposite direction. Moreover it should be exposed to the desired amount of voltage.

Q12. What is a laser diode?

They are a type of compact transistor having more than 2, or even 2, electrical leads. When emission results in amplified photons, given that the photons in question are confined into the lasing mode. Then the process is said to be lasing. As the photon hits the mirrors inside the laser diode, they give out a beam that diverges from the packages of the laser diode.

Q13. Define rectifiers and give its different types.

A rectifier is an electrical device which is responsible for the conversion of Alternating Current into Direct Current. The current inside a rectifier only flows in a single unilateral direction. The different types of rectifiers are:

  • Half-wave: a type of rectifier that has only a single pn junction
  • Full wave: a type of rectifier that has two pn junctions

Q14. What is the difference between NPN and PNP transistors?

Inside an NPN current, there are two rules that state the flow of current:

  • If there is no current flowing from A to D, it means there will be no current flowing from X to Z.
  • If there is currently flowing from A to D, it means there will be current that is allowed to flow from X to Z.

On the other hand, in a PNP transistor, there are 2 rules too, however, they are opposite of those used in the NPN transistors, that means:

  • When there is currently flowing from A to D, there is no current that is flowing from X to Z
  • Current flows from X to Z  when there is no current flow from A to D.

Q15. What is a transistor?

A transistor is a semiconducting device that helps in exemplification of the electrical signals or electrical power. Composed of semiconducting material, there should be at least 3 terminals in their connection via an external circuit. It is also reffered as  a combination of many n-type and p-type semiconductors.


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Q16. Why do we use a transistor?

The job of a transistor is to amplify the input current. However it will increase the output. In other terms, electrical current/signals and electrical power increases with the help of transistors..

Q17. What will be the outcome in a circuit when resistance is halved?

The total current will be double of its original state.

Q18. What will happen in a circuit if the total current in the system is doubled?

Doubling of circuit will result in half resistance.

Q19. What will be the outcome of voltage in a circuit if the string of resistors is placed in a series?

In a series setup, the resistors will be equally dividing the proportion of voltage into their respective values.

Q20. Differentiate between an analogue and a digital circuit?

  • An analogue circuit is a type of circuit that can work on continuous signals that are pre-valued, whereas in a digital circuit, the signal can exist only in binary, that is 0 or 1’s.
  • Within an analogue circuit, there is no conversion of the signal that received at the input before the transmission. It rather directly proceeds with the different logic operation. It produces an output that is analogue in nature. On the other hand, within a digital circuit, before the signal begin its transmission, the signal converts itself into digital data.
  • As analogue circuits require no conversion therefore, there is no probability of losing any form of information. However during the conversion period in a digital circuit, there is a risk of losing information as the signal is in digital form.
  • The final difference to mention is that while analogue circuits provide little no flexibility, their digital counterparts promote and have a high range of flexibility to offer its users.


This article was a broad description of the basic electrical engineering interview questions. While this cheat sheet offers you an understanding of the interview questions for electrical engineer, you must never underestimate the power of your textbook. Though this article presents a comprehensive guide of the frequently asked electrical engineering interview questions and answers, you can always have your book as a handy partner.

One should have a grasp of the technical knowledge questions that test the theoretical understanding of the candidate. Unlike managerial posts, where personality and leadership abilities are of paramount importance, though these are important even while you are facing the interview questions for electrical engineer, theoretical knowledge takes precedence over other matters.


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