We are providing you the top 10 electrical engineering interview questions and answers. These are the Most Asked EEE Interview Questions and Most Popular EEE Interview Questions. However, previously we had provided the L&T interview questions and answers. In your technical round interview questions following questions are important to help you and ensures to answer to the interviewer.
Below are the basic electrical engineering questions with answers are provided. Which must be known to every electrical engineer or EEE students so that the fresher’s also got their placement easily. Before the starting of the question and answers series, you must read the first two questions which are very basic and popular electrical engineering interview questions.
TWO IMPORTANT ELECTRICAL ENGINEERING INTERVIEW QUESTIONS AND ANSWERS
Q. What is Electrical Engineering?
Answer – Electrical engineering is a field of engineering that generally deals with the study and application of electricity, electronics, and electromagnetism. This field first became an identifiable occupation in the latter half of the 19th century after commercialization of the electric telegraph, the telephone, and electric power distribution and use. Subsequently, broadcasting and recording media made electronics part of daily life. The invention of the transistor, and later the integrated circuit, brought down the cost of electronics to the point they can be used in almost any household object.
Q. What are Sub-disciplines of Electrical Engineering?
Answer – Following are the sub-disciplines of electrical engineering:
- Signal processing
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Electrical Engineering Interview Questions And Answers
Q1. Mention what are the different colors on wires indicates?
Answer – This is a must be known for any Electrical Engineer. It is the basic electrical engineering interview questions and answers.
- Black wire: This wire is used for power supply in all circuits. Any circuits with this color are 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 the 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
Q2. Compare JFET and MOSFET.
Answer – Comparison of JFET and MOSFET:
- JFET’s can only be operated in the depletion mode whereas MOSFET’s can be operated in either depletion or in enhancement mode. In a JFET, if the gate is forward-biased, excess-carrier injunction occurs and the gate current is substantial.
- MOSFET’s have input impedance much higher than that of JFET. Thus is due to negligible small leakage current.
- JFET’s have characteristic curves flatter than that of MOSFET is indicating a higher drain resistance.
- When JFET is operated with a reverse bias on the junction, the gate current IG is larger than it would be in a comparable MOSFET.
Q3. Explain thin film resistors and wire-wound resistors
Answer – (a) Thin film resistors- It is constructed as a thin film of resistive material is deposited on an insulating substrate. Desired results are obtained by either trimming the layer thickness or by cutting helical grooves of suitable pitch along its length. During this process, the value of the resistance is monitored closely and cutting of grooves is stopped as soon as the desired value of resistance is obtained.
(b) Wire wound resistors – length of wire wound around an insulating cylindrical core are known as wire wound resistors. These wires are made of materials such as Constantan and Manganin because of their high resistivity, and low-temperature coefficients. The complete wire wound resistor is coated with an insulating material such as baked enamel
Q4. What happens when two positively charged material is placed together?
Answer – When two positively charged material place together it will repel.
Q5. What is referred to the electron in the outer orbit?
Answer – Electron in the outer orbit is known as valence.
Q6. Define the following terms:-
- Maximum demand
- Reserve generating capacity
- Availability (operational)
- Reliability: It is the capacity of the power system to serve all power demands without failure over long periods.
- Maximum Demand: It is maximum load demand required in a power station during a given period.
- Reserve generating capacity: Extra generation capacity installed to meet the need of scheduled downtimes for preventive maintenance is called reserve generating capacity.
- Availability: As the percentage of the time a unit is available to produce power whether needed by the system or not.
Q7. Define the term Capacitance and Inductance?
- Capacitance: It is the amount of charge that is stored in 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 the current change in the primary coil.
Q8. What is a differential amplifier? Also, explain CMRR.
Answer – Differential Amplifier: The amplifier, which is used to amplify the voltage difference between two input lines neither of which is grounded, is called differential amplifier. This reduces the amount of noise injected into the amplifier because any noise appearing simultaneously on both the input terminals as the amplifying circuitry rejects it being a common mode signal. CMRR: It can be defined as the ratio of differential voltage gain to commonly made voltage gain. If a differential amplifier is perfect, CMRR would be infinite because in that case common mode voltage gain would be zero.
Q9. Mention what are a different kind of cables used for transmissions?
Answer – Cables are categorized into three forms according to its thermal capacity
- Low tension cables- transmits voltage up to 1000 volts
- High tension cables- transmits voltage up to 23000 volts
- Super tension cables- transmits voltage up to 66kv to 132kv
Q10. Explain RLC circuit?
Answer – 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.
Q11. Explain how you decide what size of electrical wire do you need?
Answer – Wire is sized by American Wire Gauge system. Your installation of conductors will depend on a few factors like the gauge of the wire, wire capacity, etc. For wires, smaller the wire gauge larger the ampacity or capacity of the wire to handle the current. For example, low voltage lighting and lamp cords will have 18 gauge, electric furnaces or large electric heaters are of 6 gauge.
Q12. Mention what are the types of semi-conductors?
Answer –There are two types of semiconductors intrinsic and extrinsic. Again in extrinsic semiconductors, you will have N-type semiconductors and P-type semiconductors.
Q 13. State Maximum power transfer theorem.
Answer – The Maximum power transfer theorem explains about the load that a resistance will extract from the network. This includes the maximum power of the network and in this case, the load resistance is being been equal to the resistance of the network and it also allows the resistance to be equal to the resistance of the network. This resistance can be viewed by the output terminals and the energy sources can be removed by leaving the internal resistance behind.
Q14. Explain what is transistors comprised of?
Answer – Transistors are comprised of several combinations of n-type and p-type semiconductors.
Q15. Mention what is the role of a transistor in Circuit?
Answer – Transistor has the ability to amplify the current, due to the reason that output power can be higher than the input power.
Q 16. State Thevenin’s Theorem.
Answer – According to thevenin’s theorem, the current flowing through a load resistance Connected across any two terminals of a linear active bilateral network is the ratio open circuit voltage (i.e. the voltage across the two terminals when RL is removed) and the sum of load resistance and internal resistance of the network. It is given by Voc / (Ri + RL).
Q17. Mention how NPN and PNP transistor works?
Answer – 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
Q18. What will be current if the resistance total in series circuit doubles?
Answer – If the resistance total in a series circuit doubles the current will reduce to half.
Q19. What happens if the series current double?
Answer – If the series current gets double then, the resistance is halved.
Q20. Name the types of motors used in vacuum cleaners, phonographic appliances, vending machines, refrigerators, rolling mills, lathes, power factor improvement, and cranes.
Answer – Following motors are used: –
- Vacuum cleaners – Universal motor.
- Phonographic appliances – Hysteresis motor.
- Vending machines – Shaded pole motor.
- Refrigerators – Capacitor split phase motors.
- Rolling mills – Cumulative motors.
- Lathes – DC shunt motors.
- Power factor improvement – Synchronous motors.
Q21. Explain what does a string of resistors in a series will do?
Answer – When a string of resistors in a series will divide the source voltage into proportion to their values.
Q22. What is meant by reverse polarity and how it can be fixed?
Answer – Reverse polarity is referred to 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 resolve the problem. If it persists, a licensed electrician will be needed.
Q23. Explain what rectifiers are and what are the types of rectifiers?
Answer – 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
Q24. What is a slip in an induction motor?
Answer – Slip can be defined as the difference between the flux speed (Ns) and the rotor speed (N). The speed of the rotor of an induction motor is always less than its synchronous speed. It is usually expressed as a percentage of synchronous speed (Ns) and represented by the symbol ‘S’.
Q25. Explain what is Zener diode?
Answer – Zener diode is a type of seme-conductor diode that allows current to flow in the opposite direction when exposed to enough voltage.
Q26 Explain what is laser diodes?
Answer – 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.
Q27. Explain the application of storage batteries.
Answer – Storage batteries are used for various purposes, some of the applications are mentioned below:
- For the operation of protective devices and for emergency lighting at generating stations and substations.
- For starting, ignition, and lighting of automobiles, aircraft etc.
- For lighting on steam and diesel railways trains.
- As a supply power source in a telephone exchange, laboratories, and broadcasting stations.
- For emergency lighting at hospitals, banks, rural areas where electricity supplies are not possible.
Q28. How can you relate power engineering with electrical engineering?
Answer – Power engineering is a subdivision of electrical engineering. It deals with generation, transmission, and distribution of energy in electrical form. The design of all power equipment also comes under power engineering. Power engineers may work on the design and maintenance of the power grid i.e. called on grid systems and they might work on off-grid systems that are not connected to the system.
Q29. How does Zener phenomenon differ from Avalanche breakdown?
Answer – The phenomenon when the depletion region expands and the potential barrier increases leading to a very high electric field across the junction, due to which suddenly the reverse current increases under a very high reverse voltage is called Zener effect. Zener-breakdown or Avalanche breakdown may occur independently or both of these may occur simultaneously. Diode junctions that breakdown below 5v is caused by Zener Effect. Junctions that experience breakdown above 5v is caused by avalanche-effect. The Zener-breakdown occurs in heavily doped junctions, which produce narrow depletion layers. The avalanche breakdown occurs in lightly doped junctions, which produce wide depletion layers.
Q30. Explain forward resistance, static resistance and dynamic resistance of a PN junction diode.
- Forward Resistance: Resistance offered in a diode circuit, when it is forward biased, is called forward-resistance.
- DC or Static Resistance: DC resistance can be explained as the ratio of the dc voltage across the diode to the direct current flowing through it.
- AC or Dynamic Resistance: It can be defined as the reciprocal of the slope of the forward characteristic of the diode. It is the resistance offered by a diode to the changing forward current.