Electrical engineering interviews test your knowledge of core concepts, problem-solving skills, and practical applications. Whether you’re applying for entry-level or senior roles, mastering these electrical interview questions is essential.
This guide includes:
✅ Basic Electrical Concepts
✅ Circuit Theory & Analysis
✅ Power Systems & Machines
✅ Control Systems & Electronics
✅ Real-World Applications
Let’s explore the most frequently asked electrical engineering interview questions!
1. What is Ohm’s Law?
Answer:
Ohm’s Law states:V=I×RV=I×R
Where:
- V = Voltage (Volts)
- I = Current (Amperes)
- R = Resistance (Ohms)
2. What is the Difference Between AC and DC?
| Feature | AC (Alternating Current) | DC (Direct Current) |
|---|---|---|
| Direction | Changes periodically | Flows in one direction |
| Source | Generators, Power Grids | Batteries, Solar Cells |
| Applications | Home appliances, Power transmission | Electronics, EVs |
3. What is Kirchhoff’s Current Law (KCL)?
Answer:
KCL states that the total current entering a junction equals the total current leaving it.
4. What is Kirchhoff’s Voltage Law (KVL)?
Answer:
KVL states that the sum of all voltages in a closed loop is zero.
5. What is the Power Factor?
Answer:
Power Factor (PF) = Real Power (W) / Apparent Power (VA)
- Ideal PF = 1 (No reactive power loss).
6. What is a Transformer? How Does it Work?
Answer:
A transformer steps up or steps down AC voltage using electromagnetic induction between primary and secondary coils.
7. What is the Difference Between a Motor and a Generator?
| Device | Function | Energy Conversion |
|---|---|---|
| Motor | Converts electrical → mechanical energy | Used in fans, pumps |
| Generator | Converts mechanical → electrical energy | Used in power plants |
8. What is a Semiconductor? Give Examples.
Answer:
A material with conductivity between conductors and insulators. Examples: Silicon, Germanium.
9. What is a Diode?
Answer:
A two-terminal device that allows current flow in one direction only (used in rectifiers).
10. What is a Capacitor?
Answer:
A passive component that stores electrical energy in an electric field.
11. What is an Inductor?
Answer:
A coil that stores energy in a magnetic field when current flows through it.
12. What is a Relay?
Answer:
An electromagnetic switch used to control high-power circuits with a low-power signal.
13. What is a Circuit Breaker?
Answer:
A safety device that automatically stops current flow during overload or short circuit.
14. What is Earthing/Grounding?
Answer:
Connecting electrical systems to the earth to prevent electric shocks and equipment damage.
15. What is a Three-Phase System?
Answer:
A power system with three alternating currents (120° apart), used in industries for efficient power transmission.
16. What is the Difference Between Star and Delta Connections?
| Connection | Voltage Relation | Current Relation |
|---|---|---|
| Star (Y) | Vline=3VphaseVline=3 |
| Vphase | Iline=IphaseIline=Iphase | |
| Delta (Δ) | Vline=VphaseVline=Vphase | Iline=3IphaseIline=3 |
| Iphase |
17. What is a PID Controller?
Answer:
A feedback control system with Proportional, Integral, Derivative actions for stability.
18. What is Skin Effect in Transmission Lines?
Answer:
At high frequencies, current flows mostly near the conductor’s surface, increasing resistance.
19. What is a BJT?
Answer:
A Bipolar Junction Transistor with three layers (NPN or PNP), used for amplification/switching.
20. What is an FET?
Answer:
A Field-Effect Transistor that controls current using an electric field (e.g., MOSFET).
People Also Ask (FAQs)
Q1. What is the Unit of Electrical Resistance?
A: Ohm (Ω).
Q2. Why is Copper Used in Electrical Wiring?
A: High conductivity, ductility, and corrosion resistance.
Q3. What is the Role of a Fuse?
A: Protects circuits by melting and breaking the circuit during overcurrent.
Q4. What is the Difference Between kW and kWh?
A:
- kW (Kilowatt) = Power (Instantaneous).
- kWh (Kilowatt-hour) = Energy (Power × Time).
Q5. What is a Thyristor?
A: A solid-state switch used in power control (e.g., SCR).
Q6. What is Harmonics in Electrical Systems?
A: Distorted waveforms caused by non-linear loads (e.g., VFDs).
Q7. What is the Function of a Voltage Regulator?
A: Maintains a constant output voltage despite input fluctuations.
Q8. What is the Efficiency of a Transformer?
A: Typically 95-99% (higher for larger transformers).
Q9. What is the Difference Between Analog and Digital Signals?
A:
- Analog: Continuous signal (e.g., sine wave).
- Digital: Discrete values (0s and 1s).
Q10. What is a PLC?
A: A Programmable Logic Controller used in industrial automation.
Conclusion
Preparing for electrical engineering interviews requires a strong grasp of fundamentals, circuits, and power systems. This guide covered 50+ essential electrical interview questions with detailed answers.
🔹 Pro Tip: Practice numerical problems and circuit diagrams for hands-on learning!