What are the best interview questions for an electrical engineer?

1) Happens when two positively charged materials are placed together?

It repels when two positively charged materials are placed together.

2) What is the electron in outer orbit?

Valence is the name given to an electron in the outer orbit.

3) What is the definition of Capacitance/Inductance?

  • Capacitance is simply the amount of charge stored in a capacitor at a particular voltage.
  • Inductance is the property of a coil that resists any changes in the electric current flowing through them. When a secondary coil resists changes in current in the primary coil, mutual inductance occurs.

4) What is the difference between alternator and generator?

Generator and alternator both work on the same principle. They convert mechanical energy into electric energy.

  • Generator: This converts induced electromagnetic force (emf) into direct current. It is based on a stationary magnetic field and revolving conducting which rolls on the armatures riding against each other with slip rings or brushes.
  • Alternator: It is equipped with a stationary and rotating magnetic armature to provide high voltage, and a stationary magnetic field.

5) Describe the various types of transmission cables.

Three types of cables are available depending on their thermal capacity

  • Low tension cables – transmit voltage up to 1000 volts
  • High tension cables transmit voltage up to 23000 Volts
  • Super tension cables transmit voltage from 66kv up to 132kv

6) What are the colors of wires?

This is an essential question for every good electrical engineer.

  • Black wire: This is the wire used to supply power for all circuits. This color is hot and live in circuits. It should never be used as a neutral or ground cable.
  • Red wire: This is a secondary wire at 220 volts and can be used for interconnection. The red wire can be joined to another red or black wire.
  • The blue and yellow wires: These wires can also carry power, but they are not used to wire the outlets for common plug in electrical devices. These wires are used to pull the live wire through the conduct. Yellow wire will be found in fan, structure lights and switched outlets.
  • Gray and white: This wire can be used as a neutral. It carries the current (unbalanced loads) to the ground. It can be joined to gray and white wires only.
  • Green: This is connected to an outlet box’s grounding terminal and runs from there to an electric panel’s ground bus bar.

7) Explain RLC circuit?

An RLC circuit is an electrical circuit that consists of a resistor, inductor and capacitor connected in parallel or in series. This circuit is referred to as a second-order circuit because any voltage or current within the circuit can be described using a second order differential equation.

8) Tell us how you determine the size of an electrical wire you will need.

American Wire Gauge is used to size wire. The gauge and wire capacity will affect the way you install conductors. The wire’s gauge will determine the current handling capacity or ampacity. Low voltage lighting and lamp cords have 18 gauge while electric furnaces and large electric heaters have 6 gauge.

9) What are the different types of semi-conductors you know?

There are two types: intrinsic and extrinsic semi-conductors. Extrinsic semiconductors will also have P-type and N-type semiconductors.

10) Describe what transistors are made of.

Transistors can be made up of many combinations of semi-conductors of the n- and p-type types.

11) What is the role of the transistor in Circuit?
Transistor can amplify the current. This is because the output power can be greater than the input power.

12) How does the NPN and PNP transistor work?

NPN can be used in a circuit.

  • There is no current from A to D = there is no flow from X and Z
  • Current flowing from A-D = Current allowed to flow between X and Z

When PNP is used

  • There is no current allowed from A to D = No current is allowed from X to Z
  • Current flowing from A-D = No current flow between X and Z

13) If the resistance total in series circuits doubles, what will be the current?

The current will drop to half if the resistance in a series circuit is doubled.

14) What happens to the series current if it doubles?

The resistance will be halved if the series current is doubled.

15) Describe what a series of resistors will do.

A string of resistors placed in a series will distort the source voltage according to their values.

16) What does reverse polarity mean and how can it be fixed?

If one or more of your outlets are not connected correctly, you will be referred to as reverse polarity. Check the wiring connection at the outlet to fix reverse polarity. Also inspect the receptacle. Receptacles with reverse polarity have the white wire connected to the hot side while the black wire is connected to the neutral. If this is the case, swap the wires to resolve the problem. If the problem persists, an electrician licensed in that area will be required.

17) Describe what rectifiers are and the different types.

A rectifier is an electric device that converts A.C (or alternating current) into direct current (D.C), which flows only in one direction. There are several types of rectifiers.

  • Half wave rectifier: It uses a single p-n junction
  • Two p-n junctions are used to create a full wave rectifier

18) Describe Zener diode.

A type of semeconductor diode called Zener diode allows current to flow in opposite direction when it is exposed to sufficient voltage.

19.) What is the difference between an analog and digital circuit?



  • These circuits work on continuous value signals
  • The circuit executes various logic operations directly and produces an analog output. There is no need to convert the input signal before transmitting.
  • As there is no way to convert information, it is impossible to lose any information.
  • Analogue lacks flexibility
  • These circuits work on signals that exist at the two levels 0 and 1
  • The signal is first converted into digital form before it can be transmitted.
  • Signal conversion can result in the loss of significant amounts of information
  • Digital circuits are designed to be flexible

20) Describe laser diodes.

Laser diodes can be described as compact transistor-like packages that have two or more leads. When stimulated emission causes photons to be amplified in the lasing mode, it is called Lasing. These photons bounce back and forth between the front and back mirrors, resulting in a diverging beam that is emitted from the laser diode package.


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