Basic Electronics Questions for Interview

Electronics Engineering students need to face some Basic Electronics Questions whether they are preparing for an interview or viva voce. So, this article gives you few Basic Electronics Questions for Interview and other competetive exams.

Generally, you need to refer a variety of books in order to cover the ocean of topics in Electronics. To make it easy for you guys, I’ve collected a few basic electronics questions from different topics and organized them into different sections.

Initially, I’ll be concentrating majorly on multiple choice type questions and in the future I’ll add the explanations and some short answer type questions.

Basic Introduction Questions

1. What is an ideal voltage source?
Answer: A device with zero internal resistance.

2. What is an ideal current source?
Answer: A device with infinite internal resistance.

3. What is a practical voltage source?
Answer: A device with small internal resistance.

4. What is a practical current source?
Answer: A device with large internal resistance.

5. The voltage out of an ideal voltage source is
A. Zero
B. Constant
C. Load resistance dependent
D. Internal resistance dependent
Answer: B

6. The current out of an ideal current source is
A. Zero
B. Constant
C. Load resistance dependent
D. Internal resistance dependent
Answer: B

7. The path between two points along which an electrical current can be carried is called
A. A network
B. A relay
C. A circuit
D. A loop
Answer: C

8. The formula for current as per Ohm’s Law is
A. Voltage / Resistance
B. Resistance * Voltage
C. Voltage + Resistance
D. Resistance / Voltage
Answer: A

9. The unit of electrical resistance is
A. Volt
B. Amp
C. Ohm
D. Coulomb
Answer: C

10. In a constant voltage DC circuit, when the resistance increases, the current will
A. Decrease
B. Stop
C. Increase
D. Remains constant
Answer: A

Basic Semiconductor Theory Questions

1. Number of valence electrons in a silicon atom are
A. 1
B. 4
C. 8
D. 16
Answer: B

2. The most commonly used semiconductor element is
A. Silicon
B. Germanium
C. Gallium
D. Carbon
Answer: A

3. Copper is a
A. Insulator
B. Conductor
C. Semiconductor
D. Super Conductor
Answer: B

4. Number of protons in the nucleus of a silicon atom are
A. 4
B. 14
C. 29
D. 32
Answer: B

5. The valence electron of a conductor are also called as
A. Bound electron
B. Free electron
C. Nucleus
D. Proton
Answer: B

6. An intrinsic semiconductor at room temperature has
A. A few free electrons and holes
B. Many holes
C. Many free electrons
D. No holes
Answer: A

7. At room temperature, an intrinsic semiconductor has some holes in it due to
A. Doping
B. Free electrons
C. Thermal energy
D. Valence electrons
Answer: C

8. The number of holes in an intrinsic semiconductor is
A. Equal to number of free electrons
B. Greater than number of free electrons
C. Less than number of free electrons
D. None of the above
Answer: A

9. Holes act as
A. Atoms
B. Crystals
C. Negative charges
D. Positive charges
Answer: D

10. Pick the odd one in the group
A. Conductor
B. Semiconductor
C. Four valence electrons
D. Crystal structure
Answer: A

11. To produce P-type semiconductors, you need to add
A. Trivalent impurity
B. Carbon
C. Pentavalent impurity
D. Silicon
Answer: A

12. Electrons are the minority carriers in
A. Extrinsic Semiconductors
B. p-type Semiconductors
C. Intrinsic Semiconductors
D. n-type Semiconductors
Answer: D

13. A p-type semiconductor contains
A. Holes and Negative ions
B. Holes and Positive ions
C. Holes and Pentavalent atoms
D. Holes and Donor atoms
Answer: A

14. How many electrons does pentavalent atoms have?
A. 1
B. 3
C. 4
D. 5
Answer: D

15. Negative ions are
A. Atoms that obtained a proton
B. Atoms that lost a proton
C. Atoms that obtained an electron
D. Atoms that lost an electron
Answer: C

16. What is the result of Ionization in PN Junction on either side of potential barrier?
A. Barrier Voltage
B. Junction
C. Depletion Region
D. Forward Voltage
Answer: C

17. The cause of Depletion Region is __________
A. Diffusion
B. Ions
C. Doping
D. Forward Voltage
Answer: A

18. Which of the following is a Semiconductor?
A. Argon
B. Carbon
C. Mica
D. Ceramic
Answer: B

19. Doping material among the following is
A. n-type Semiconductor
B. Majority Carriers
C. Extrinsic Semiconductor Material
D. Pentavalent Material
Answer: D

20. We can easily activate minority carriers using
A. Forward Voltage
B. Doping
C. Heat
D. Pressure
Answer: C

Basic Semiconductor Diode Questions

1. Depletion layer is caused by
A. Doping
B. Recombination
C. Barrier potential
D. Ions
Answer: B

2. The reverse current in a diode is usually
A. Very small
B. Very large
C. Zero
D. In the breakdown region
Answer: A

3. Avalanche in Diode occurs at
A. Barrier potential
B. Depletion layer
C. Knee voltage
D. Breakdown voltage
Answer: D

4. The potential barrier of a silicon diode is
A. 0.3 V
B. 0.7 V
C. 1 V
D. 5V
Answer: B

5. The reverse saturation current in a Silicon Diode is _____ than that of Germanium Diode
A. Equal
B. Higher
C. Lower
D. Depends on temperature
Answer: C

6. A Diode is a
A. Bilateral Device
B. Nonlinear Device
C. Linear Device
D. Unipolar Device
Answer: C

7. The diode current is large for which condition
A. Forward Bias
B. Inverse Bias
C. Poor Bias
D. Reverse Bias
Answer: A

8. The output voltage signal of a bridge rectifier is
A. Half-wave
B. Full-wave
C. Bridge-rectified signal
D. Sine wave
Answer: B

9. If the maximum DC current rating of diodes in Bridge Rectifier is 1A, what is the maximum DC load current?
A. 1A
B. 2A
C. 4A
D. 8A
Answer: B

10. Voltage multipliers produce
A. Low voltage and low current
B. Low voltage and high current
C. High voltage and low current
D. High voltage and high current
Answer: C

11. What is a Clipper?
Answer: A circuit that removes a part (positive or negative) of a waveform so that it doesn’t exceed a certain voltage level.

12. What is a Clamper?
Answer: A circuit that adds a DC voltage (positive or negative) to a wave.

13. Zener diode can be described as
A. A rectifier diode.
B. A device with constant – voltage.
C. A device with constant – current.
D. A device that works in the forward region.
Answer: B

14. If the Zener Diode is connected in wrong polarity, the voltage across the load is
A. 0.7 V
B. 10 V
C. 14 V
D. 18 V
Answer: A

15. Since diodes allow flow of current in only one direction, they can be used for
A. Current Limiting
B. Reverse Polarity Protection
C. Storing Charge
D. Voltage Regulation
Answer: B

16. When you test a good diode with a multimeter, it shows
A. Low resistance when forward biased or reverse biased
B. High resistance when forward biased or reverse biased
C. High resistance when forward biased and Low resistance when reverse biased
D. Low resistance when forward biased and High resistance when reverse biased
Answer: D

17. When does current flow in a PN junction?
A. When both p-type and n-type elements are at same potential
B. When there is no potential at either p-type or n-type elements
C. When p-type element is at more positive potential than n-type
D. When n-type element is at more positive potential than n-type
Answer: C

18. Clamping Circuits are generally used in
A. TV Transmitters and Receivers
B. FM Transmitters
C. Signal Generators (Square, Trapezoid, etc.)
D. All the above
Answer: D

19. Units of measurement for forward bias and reverse current of a diode are
A. µA and µA
B. mA and µA
C. µA and mA
D. mA and mA
Answer: B

20. What graphical method is used for modelling Diode Characteristics
A. Exponential Method
B. Small Signal Approximation
C. Iteration Method
D. Constant Voltage Drop Method
Answer: A

Basic Transistor Questions

1. Number of PN Junctions in a Transistor
A. One
B. Two
C. Three
D. Four
Answer: B

2. The doping concentration of Base in NPN Transistor is
A. Lightly Doped
B. Moderately Doped
C. Heavily Doped
D. Not Doped
Answer: A

3. The Base – Emitter Diode (Base – Emitter Junction) in an NPN Transistor is
A. Doesn’t conduct
B. Forward Biased
C. Reverse Biased
D. Operates in breakdown region
Answer: B

4. The size comparison between Base, Emitter and Collector is
A. Base > Collector > Emitter
B. Emitter > Collector > Base
C. Collector > Emitter > Base
D. All are equal
Answer: C

5. The Base – Collector Diode (Base Collector Junction) is usually
A. Reverse Biased
B. Forward Biased
C. Breakdown Region
D. No Conduction
Answer: A

6. The DC Current Gain of a Transistor is
A. Ratio of Emitter Current to Collector Current
B. Ratio of Base Current to Emitter Current
C. Ratio of Collector Current to Base Current
D. Ratio of Base Current to Collector Current
Answer: C

7. If base current is 100µA and current gain is 100, then collector current is
A. 1A
B. 10A
C. 1mA
D. 10mA
Answer: D

8. The majority carriers in NPN and PNP Transistors are
A. Holes and Electrons
B. Electrons and Holes
C. Acceptor Ions and Donor Ions
D. None
Answer: B

9. A Transistor acts as a
A. Voltage Source and a Current Source
B. Current Source and a Resistor
C. Diode and Current Source
D. Diode and Power Supply
Answer: C

10. The relation between Base Current IB, Emitter Current IE and Collector Current IC is
A. IE = IB + IC
B. IB = IC + IE
C. IE = IB – IC
D. IC = IB + IE
Answer: A

11. The total power dissipated by a transistor is a product of collector current and
A. Supply Voltage
B. 0.7V
C. Collector – Emitter Voltage
D. Base – Emitter Voltage
Answer: C

12. The input impedance of Common Emitter Configuration is
A. Low
B. High
C. Zero
D. Very High
Answer: A

13. The output impedance of Common Emitter Configuration is
A. Low
B. Very Low
C. High
D. Zero
Answer: C

14. Two types of Bipolar Junction Transistors (BJTs) are
A. nnn and ppp
B. npn and pnp
C. pnn and npp
D. nnp and ppn
Answer: B

15. What are the common faults in BJT?
A. Internal Short
B. Open Bias Resistor
C. External Open and
D. nnp and ppn
Answer: B

16. The usual operating region of Transistors in Digital Circuits is
A. Active Region
B. Linear Region
C. Breakdown Region
D. Cutoff and Saturation Region
Answer: D

17. Another name for Emitter Follower Configuration is
A. Common Base Amplifier
B. Common Emitter Amplifier
C. Common Collector Amplifier
D. Darlington Pair
Answer: C

18. BJT is a _________ and a FET is ________
A. Bipolar and Unipolar
B. Bipolar and Bipolar
C. Unipolar and Unipolar
D. Unipolar and Bipolar
Answer: A

19. The current gain in Common Base configuration (α) is
A. Ratio of Base Current to Emitter Current (IB/IE)
B. Ratio of Collector Current to Emitter Current (IC/IE)
C. Ratio of Collector Current to Base Current (IC/IB)
D. None
Answer: B

20. Relation between α and ß is
A. α = ß / (ß + 1)
B. ß = α / (1 – α)
C. α = ß * (ß + 1)
D. α = ß / (ß – 1)
Answer: Both A and B