20 Electrical Engineering Interview Questions & Answers

1) What happens when two positively charged material is placed together?

When two positively charged material place together it will repel.

2) What is referred to the electron in the outer orbit?

Electron in the outer orbit is known as valence.

3) Define the term Capacitance and Inductance?

  • Capacitance: It is the amount of charge that is stored inside a capacitor at a given voltage.
  • Inductance: It is defined as the property of a coil to resist any changes in electric current flowing through it. Mutual inductance happens when a secondary coil opposes current change in the primary coil.

4) Mention what is the difference between generator and alternator?

Both generator and alternator work on the same principle they convert mechanical energy into electrical energy.

  • Generator: It converts induced emf (Electro Motive Force) into direct current, where it based on stationary magnetic field and revolving conductor which rolls on the armatures with slip rings and brushes riding against each other.
  • Alternator: It has rotating magnetic and stationary armature for high voltage and stationary magnetic field and a rotating armature for low voltage

5) Mention what are the different kind of cables used for transmissions?

Cables are categorized into three forms according to its thermal capacity

  • Low tension cables- transmits voltage upto 1000 volts
  • High tension cables- transmits voltage up to 23000 volts
  • Super tension cables- transmits voltage up to 66kv to 132kv


6) Mention what are the different colors on wires indicates?

This is a must know question for any good Electrical Engineer

  • Black wire: This wire is used for power supply in all circuits. Any circuits with this color is considered hot or live. It is never used for a neutral or ground wire.
  • Red wire: This color wire is a secondary live wire in a 220 volt circuit and used in some types of interconnection. You can join the red wire to another red wire or to a black wire
  • Blue and Yellow wire: These wires are also used to carry power but are not wiring the outlets for common plug-in electrical devices. They are used for the live wire pulled through the conduct. You will see yellow wire in the fan, structure lights, and switched outlets.
  • White and Gray: This color wire is used as a neutral wire. It carries the current (unbalanced load) to the ground. You can join white and gray only to other white and gray wires
  • Green: It is connected to the grounding terminal in an outlet box and run from the outlet box to the ground bus bar within an electric panel

7) Explain RLC circuit?

An RLC circuit carries an electrical circuit consisting of a resistor (R) and inductor (L) and a capacitor (C), connected in parallel or series. This circuit is called a second order circuit as any voltage or current in the circuit can be described by a second order differential equation.

8) Explain how you decide what size of electrical wire do you need?

Wire is sized by American Wire Gauge system. Your installation of conductors will depend on a few factors like gauge of the wire, wire capacity, etc. For wires, smaller the wire gauge larger the ampacity or capacity of the wire to handle current. For example, low voltage lighting and lamp cords will have 18 gauge, electric furnaces or large electric heaters are of 6 gauge.

9) Mention what are the types of semi-conductors?

There are two types of semi-conductors intrinsic and extrinsic. Again in extrinsic semi-conductors you will have N-type semiconductors and P-type semiconductors.

10) Explain what is transistors comprised of?

Transistors are comprised of several combination of n-type and p-type semi-conductors.

11) Mention what is the role of transistor in Circuit?
Transistor has the ability to amplify the current, due to the reason that output power can be higher than the input power.

12) Mention how NPN and PNP transistor works?

In a circuit when NPN is used,

  • No current flowing from A to D = No flow from X to Z
  • Current flowing from A to D = Current allowed to flow from X to Z

When PNP is used,

  • No current flowing from A to D = Current is allowed to flow from X to Z
  • Current flowing from A to D = No current flow from X to Z

13) What will be the current if the resistance total in a series circuit doubles?

If the resistance total in a series circuit doubles the current will reduce to half.

14) What happens if the series current double?

If the series current gets double then, the resistance is halved.

15) Explain what does a string of resistors in a series will do?

When a string of resistors in a series will divide the source voltage into proportion to their values.

16) What is meant by reverse polarity and how it can be fixed?

Reverse polarity is referred in a condition where one or more of your receptacles are connected incorrectly. To fix the reverse polarity, check the wire connection at the outlet and inspect your receptacle. A receptacle with reverse polarity will have the white wire screwed to the hot side and the black wire will be connected to the neutral side, if that the case swap the wires and it will resolves the problem. If it persists, a licensed electrician will be needed.

17) Explain what rectifiers is and what are the types of rectifiers?

A rectifier is an electrical device that transforms A.C  or alternating current into direct current (D.C), which flows in only one direction. The types of rectifiers are

  • Half wave rectifier: It uses one p-n junction
  • Full wave rectifier: It uses two p-n junction

18) Explain what is Zener diode?

Zener diode is a type of seme-conductor diode that allows current to flow in the opposite direction when exposed to enough voltage.

19) Mention the difference between Analogue and Digital circuit?

Analogue Digital
  • These circuits operate on continuous valued signals
  • No conversion of the input signal required before transmitting, the circuit directly executes various logical operations and produces an analogue output
  • There is no probability of losing any information as there is no conversion
  • Analogue lacks flexibility
  •  These circuits operate on the signal which exist at two level 0’s and 1’s
  • Before the signal is transmitted, it is converted into digital form.
  • During signal conversion, amount of information is lost
  • Digital circuits anticipate high flexibility

20) Explain what is laser diodes?

Laser diodes are compact transistor like packages with two or more electrical leads. Lasing occurs when stimulated emission results into the amplification of photon confined to the lasing mode.  These photons hit back and forth between the back and front mirror, and hence a diverging beam emits from the laser diode packages.

51 replies

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  1. Avatar
    Manjula says:

    It’s a very good and very basic questions that we have to know….Thank you…..

    • Avatar
      Ramakrishnan says:

      Thanks for sharing snd good information

  2. Avatar
    Menzi Ndwandwe says:

    I want a learnership of electrical engineering I complete my N6

  3. Avatar
    Brijendra Kumar Sen says:

    It’s best site preparing Electrical Engineer for placement .

  4. Avatar
    VAMPIT says:

    nice article

  5. Avatar
    Azhar says:

    Very nice questi6

  6. Avatar
    Vidya Gupta says:

    Nice question

  7. Avatar
    mansoor says:

    I have 4 amp dc fan can i run this fan through 3.5 amp charger

    I will be thankful to you

    • Avatar
      Athanasius Emmanuel says:

      In practical terms, it is possible because the charger is within acceptable tolerance (- or + 1). The only disadvantage you will encounter is that it will take a little longer time to get charged than the actual rated 4amp charger.

    • Avatar
      Ramgouda says:

      U can run .

    • Avatar
      James madamombe says:

      Good questions ….I really like this

    • Avatar
      Surinder says:

      Yes but potential should be high of charger I.e. V

  8. Avatar
    Rajasekaran says:

    Very nice questions are prepared.It is very useful for those who remember as well as new comer in electrical fields.

  9. Avatar

    Very good questions….

  10. Avatar
    Prasanna kumar M E says:

    Vv good questions sir

  11. Avatar
    Anji says:

    Basics are important, without this we can’t understand subject ok thanks

  12. Avatar
    Yashwanth says:

    Nice questions for better improvement of basics

  13. Avatar
    Samson says:

    I like so interesting 💥

  14. Avatar
    sakthivel says:

    super bro

  15. Avatar
    Sreenath v Bestha says:

    Basic knowledge for electrical & electronics engineers

  16. Avatar
    viswajeet says:

    Thank you so much for providing this kind of basic question.

    Request you to provide more question with answers.

  17. Avatar
    Virupaksha says:

    I like

  18. Avatar
    Bharath B says:

    Simple & good

  19. Avatar
    Ganesh L autade says:

    Best👍💯 carrier question And answer🙏thanks you SO much 🙏

  20. Avatar
    Atinkut.T says:

    it is exeleent,but add more…..

  21. Avatar
    Nkosingiphile says:

    Great questions

  22. Avatar
    Ramya says:

    Nice questions

  23. Avatar
    Priyanka says:

    Nice sir

  24. Avatar
    Apamaku Ismail says:

    Wonderful it has sharpened my brain

  25. Avatar
    Mamatha says:

    It’s nice and useful questions for us..
    Thank you for that..

  26. Avatar
    Ramandeep Singh says:

    Thanks 😘

  27. Avatar
    Navya boggula says:

    Really I was very useful as these questions are very basic especially for the interview purpose

  28. Avatar
    A shigal says:

    Its a very very splendid and basic question that we have to know.. Ty so much

  29. Avatar
    Mayur Pawar says:

    Thank you very much sir, for this important interview questions.

  30. Avatar
    Mayur Pawar says:

    Thank you very much sir, for this important interview questions..

  31. Avatar
    Tejeswar Pattnaik says:

    Very good topic

  32. Avatar
    otswere samuel says:

    Very nice question and answer love it

  33. Avatar
    Jitendra mohapatra says:


  34. Avatar
    M B Joseph Gerald says:

    Good morning,
    This is a useful page to me. I learn many things related to Electrical and Electronics Engineering.
    Thank you.

  35. Avatar
    Neelam Motghare says:

    Very short brief and good revisions…

  36. Avatar
    Sunil S says:

    Most of useing the black color wire for Neutral in low volt or in medium voltage

  37. Avatar
    Anthony says:

    Nice question

  38. Avatar
    Arun D ganvit says:

    It is not good question ..

  39. Avatar
    Walde says:

    Very understood and brief.
    Good explanation

  40. Avatar
    Kamal kishor Kumar says:

    Very nice question with answers.

  41. Avatar
    Tippu says:

    It’s good to recall the basic things

  42. Avatar
    Ramu L says:

    These all questions and answers are briefly simple……..Thank you

  43. Avatar
    ANUP KUMAR says:

    Very nice question

  44. Avatar
    Muniyandi says:

    I studied blak wire is nueral red wire is live green wire is earthing and red yellow blue also live wires in three phase system.

  45. Avatar
    Akande dare femi says:

    Good question and answer

  46. Avatar
    Anwarul Hoque Mazumder says:

    Tnx for sharing good & basic knowledg.