Here are 1000 MCQs on Electronic Devices and Circuits (Chapterwise).
1. Which of the following is not an electronic device?
a) A mobile
b) A computer
c) A magnifying glass
d) A keyboard
View Answer
Explanation: A mobile, a computer and a keyboard are electronics devices because they are controlled by the flow of electrons for information processing. A magnifying glass is a non-electronic device.
2. Which of the following is not a physical component of an electronic circuit?
a) Capacitor
b) Inductor
c) Diode
d) Temperature
View Answer
Explanation: Capacitors, inductors, and diodes are the physical components of electronic circuits because they affect the flow of electrons or current in the circuit.
3. Which of the following is not a property of semiconductors used in electronic devices?
a) They excite electrons
b) They don’t emit light
c) They have high thermal conductivity
d) They have variable electrical conductivity
View Answer
Explanation: Semiconductors excite electrons. They have variable electrical conductivity and high thermal conductivity. Some compound semiconductors also emit light which is popularly known as light-emitting diodes.
4. Which of the following is the correct relationship between temperature (T) and mobility (u) of electrons in electronic circuits?
a) u ∝ T-3/2
b) u ∝ T-1/2
c) u ∝ T
d) u ∝ T-1
View Answer
Explanation: When temperature increases then the frequency of the lattice point increases and as a result collisions of electrons increases. Hence, mobility decreases. The correct relation is u ∝ T-3/2.
5. What is the effect of temperature on the recombination rate of electrons in electronic circuits?
a) Recombination rate increases with increase in the temperature
b) Recombination rate decreases with increase in the temperature
c) Recombination rate is independent of temperature
c) Recombination of electrons doesn’t occur in semiconductors
View Answer
Explanation: Recombination rate decreases when temperature increases because the electrons that are going to combine with holes in the valence bond are re-excited.
6. Which of the following is correct about semiconductors in electronic devices?
a) Elemental semiconductors have direct band gap
b) Compound semiconductors have indirect band gap
c) Extrinsic semiconductors are injected with impurities
d) Doping is done in Intrinsic semiconductors
View Answer
Explanation: Elemental semiconductors have indirect band gap. Compound semiconductors have direct band gap. Doping is done with impurities in extrinsic semiconductors, not in intrinsic semiconductors.
7. Which of the following technique can’t be used for generating electron-hole pairs in electronic devices?
a) Thermal excitation
b) Impact ionization
c) Photo excitation
d) Impurity injection
View Answer
Explanation: Electron-hole pairs can be generated by increasing temperature or ionization or photo excitation. Impurity injection is done for doping of semiconductors. This process doesn’t generate electron-hole pairs.
8. Which of the following is not correct about semiconductors in electronic devices?
a) Electrons are present below Fermi level in a semiconductor
b) Degenerated semiconductors behave like a conductor
c) Fermi level is independent of temperature and doping
d) Pentavalent atoms are used in an n-type extrinsic semiconductor
View Answer
Explanation: Fermi level is the highest level of electrons at 0K. Below Fermi level, all levels are filled with electrons. Fermi level depends on the temperature and the doping of the semiconductor.
9. Which of the following equation represents mass action law for semiconductors in electronic circuits?
a) n × p = ni2
b) n × p = ni
c) n × p = ni3
d) n × p = ni1/2
View Answer
Explanation: Mass action law states that at a constant temperature, the product of the concentration of electrons and the concentration of holes is maintained constant in any type of semiconductor.
10. Which of the following is correct about Hall Effect in electronic circuits?
a) Hall voltage is very weak in metals as compared to semiconductors
b) Hall voltage is directly proportional to the charge density
c) Hall voltage is inversely proportional to the intensity of the magnetic field
d) Intrinsic semiconductor has a positive temperature coefficient of hall constant
View Answer
Explanation: Metals have an ocean of electrons. So, there is very little difference between positive and negative charges in metals. Thus, Hall voltage is very weak in metals as compared to semiconductors.
11. Which of the following is not correct about a step-graded junction in electronic devices?
a) Diodes with step-graded junctions are slower than a normal diode
b) They are designed with abrupt junction
c) They are either p+– n or p – n+ junction
d) Depletion layer penetrates more into the lightly doped region
View Answer
Explanation: Step-graded junctions are designed with abrupt junctions. They are either p+– n or p – n+ junction and diodes with step-graded junctions are faster than the normal diodes.
12. Which of the following is correct about photo diode electronic devices?
a) P-N junction is connected in reverse bias.
b) Electron-hole pairs are generated by impurity injection in depletion layer
c) It is a photovoltaic cell
d) No external voltage is applied
View Answer
Explanation: Photo diode is a photoconductive cell. External voltage is applied and P-N junction is connected in reverse bias. Electron-hole pairs are generated by photons in the depletion layer.
13. Which of the following is wrong about solar cell electronic devices?
a) Solar cell responsivity is directly proportional to the wavelength of light
b) It produces dark current
c) It is a photovoltaic cell
d) No external voltage is applied
View Answer
Explanation: Solar cell is a photovoltaic cell. No external voltage is applied and solar cell responsivity is directly proportional to the wavelength of the incident light. It doesn’t produce dark current.
14. What type of semiconductor is used in LED electronic circuits?
a) Intrinsic semiconductor
b) Compound semiconductor
c) Degenerated semiconductor
d) Compensated semiconductor
View Answer
Explanation: LEDs need compound type semiconductors because they have direct band gap. In direct band gap, photons are easily generated when electrons release energy during recombination.
15. Which of the following semiconductor is mostly used to construct electronic circuits?
a) Silicon
b) Germanium
c) Selenium
d) Tin
View Answer
Explanation: Silicon is mostly used to construct electronic circuits because silicon has a much higher PIV (Peak Inverse Voltage) than the other semiconductors. It is also very cheap.
16. Which of the following is correct about NMOS electronic circuits?
a) It has N-substrate
b) For inversion positive voltage is applied to the gate terminal
c) For accumulation positive voltage is applied to the gate terminal
d) NMOS has holes as the majority of carriers
View Answer
Explanation: NMOS has P-substrate and it has electrons as the majority carriers. For accumulation negative voltage is applied to the gate terminal and for inversion positive voltage is applied to the gate terminal.
17. Which of the following is wrong about threshold voltage (VT) in a MOSFET electronic circuit?
a) If VT is less, channel form quickly for conductivity
b) VT can be reduced by reducing oxide layer thickness
c) VT is independent of ion implementation
d) VT can be reduced by reducing substrate doping
View Answer
Explanation: VT can be reduced by suitable ion implementation. Like in NMOS, positive donor ions are implemented to reduce repulsion to the electrons present in the channel.
18. Which of the following is the correct relationship between trans-conductance (Gm) and drain to source current (IDS) in an NMOS electronic circuit?
a) Gm ∝ IDS-3/2
b) Gm ∝ IDS-1/2
c) Gm ∝ IDS
d) Gm ∝ IDS1/2
View Answer
Explanation: Trans-conductance in NMOS is defined as the change in the drain to source current with respect to the gate to source voltage. The correct relation is Gm ∝ IDS1/2.
19. In which of the following region does BJT act as the amplifier electronic device?
a) Cut-off
b) Saturation
c) Active
d) Reverse saturation
View Answer
20. Which type of semiconductor is used in Tunnel Diode?
a) Compound semiconductor
b) Elemental semiconductor
c) Degenerated semiconductor
d) Extrinsic semiconductor
View Answer
Explanation: Degenerative N-type and degenerative p-type semiconductors are used in tunnel diodes. Tunnel diodes are used in microwave electronic devices and circuits.
21. Which of the following is false about Fermi-Dirac distribution function f(E) used to understand semiconductors in electronic circuits?
a) f(E) is the probability of finding an electron in an energy level E
b) When the temperature decreases f(E) also increases
c) f(E) doesn’t give the number of electrons in a given energy level
d) f(E) doesn’t give the number of energy levels with electrons
View Answer
Explanation: Fermi-Dirac distribution function f(E) is the probability of finding an electron in an energy level E. When temperature increases f(E) also increases.
22. An electronic circuit wire of conductivity 5.8 × 107 mho-m is subjected to an electric field of 40 mV/m. What will be its current density?
a) 2.32 × 106 A/m2
b) 1.16 × 106 A/m2
c) 4.64 × 106 A/m2
d) 4.30 × 106 A/m2
View Answer
Explanation: The current density (J) is the product of conductivity and electric field. The conductivity is 5.8 × 107 mho-m and the electric field is 40 mV/m. So, J = 5.8 × 107 × 40 × 10-3 = 2.32 × 106 A/m2.
23. Mass action law is not valid for which type of semiconductors in electronic devices?
a) Compound
b) Elemental
c) Degenerative
d) Compensated
View Answer
Explanation: Mass action law is related to the concentration of electrons and holes in a semiconductor. Degenerative type semiconductors show similar behavior to metal. So, Mass action law is not valid for them.
24. Which of the following is the correct expression of current in an intrinsic semiconductor electronic circuit?
a) ITotal = Ie + Ih
b) ITotal = Ie – Ih
c) ITotal = Ie + 2Ih
d) ITotal = 2Ie + Ih
View Answer
Explanation: When electric field is applied to an intrinsic semiconductor, electrons and holes move in the opposite direction. So, the total current will be the sum of the current due to electrons and holes.
25. When an electronic circuit is in equilibrium then which of the following equation is valid?
a) Jdrift + Jdiffusion = 1
b) Jdrift + Jdiffusion = 0
c) Jdrift + Jdiffusion = -1
d) Jdrift + Jdiffusion = 2
View Answer
Explanation: When an electronic circuit is in equilibrium then the net current density becomes 0. Current density occurs due to the drift and diffusion of ions. So, Jdrift + Jdiffusion = 0.
26. Which of the following is wrong about P-N junction diodes used in electronic devices?
a) They have three modes of operations
b) They have dynamic resistance at low-frequency AC voltage
c) They have diffusion capacitance at high-frequency AC voltage
d) They can act as ON-OFF switches
View Answer
Explanation: P-N junction diodes have two modes of operations i.e. forward and reverse bias. Forward bias is called ON switch and reverse bias is called OFF switch.
27. What is the conductivity of an extrinsic type semiconductor electronic device at 0K?
a) maximum
b) zero
c) can’t be determined
d) minimum
View Answer
Explanation: At T = 0K, conductivity will be zero because donar level ionization is zero, so no free electron is there in the conduction band. Conductivity is measured when free electrons are present in the conduction band for conduction.
28. What is the conductivity of an extrinsic type semiconductor electronic device at 300K?
a) Maximum
b) Zero
c) Can’t be determined
d) Minimum
View Answer
Explanation: At 300k, conductivity is maximum because of complete ionization of dopant levels which causes more free electrons conductivity in the conduction band.
29. Which of the following effects is responsible for violating the mass action law in degenerative type semiconductor electronic devices?
a) Thermal effect
b) Bandgap narrowing effect
c) Lattice vibration effect
d) Electronic drift effect
View Answer
Explanation: With a very high amount of doping in degenerative type semiconductors, atoms come closer. For this reason, the interatomic interaction cannot be neglected. So, the effective band gap becomes narrow.
30. Which of the following diode is used in ultra-high speed switching electronic circuits?
a) Zener diode
b) Varactor diode
c) Tunnel diode
d) Schottky diode
View Answer
Explanation: Due to tunneling, a large number of electrons penetrate through the junction, so a large amount of current is produced. And as we are considering a special diode, we can control its I-V characteristics to improve the switching speed.
31. Which of the following diode is used in adjustable band pass filter electronic circuits?
a) Zener diode
b) Varactor diode
c) Tunnel diode
d) Schottky diode
View Answer
Explanation: Band pass filter depends upon the value of the resistance and capacitance. In varactor diode, we can obtain capacitance by varying the input voltage. As capacitance becomes adjustable, it can be considered as an adjustable band pass filter.
32. Forbidden Energy gap (EG) of a semiconductor in electronic devices depends on which of the following factors?
a) Interatomic distance
b) Material constant
c) Electron affinity
d) Recombination and Generation
View Answer
Explanation: Forbidden energy gap (EG) of a semiconductor is directly proportional to the bond strength. And bond strength depends on the interatomic distance.
33. Which of the following is the correct order of turn-off times?
a) MOSFET < BJT < IGBT < SCR
b) MOSFET < IGBT < BJT < SCR
c) SCR < BJT < IGBT < MOSFET
d) BJT < MOSFET < IGBT < SCR
View Answer
Explanation: Electronic devices like MOSFET have the lowest turn-off times (nanoseconds). BJT has turn-off times in between nanoseconds to microseconds. IGBT and SCR have turn-off times of about 1 and 5 microseconds respectively.
34. Which of the following is correct relation for saturation region in a NMOS electronic circuit?
a) VDS >= VG + VT
b) VDS >= VG – VT
c) VDS <= VG – VT
d) VDS >= VG ± VT
View Answer
Explanation: For the saturation region, the drain to source voltage is greater than or equal to the difference between the gate voltage and the thermal voltage. So, VDS >= VG – VT.
35. Which of the following type of transistor is preferred in digital and analog electronic circuits?
a) BJT
b) JFET
c) MOSFET
d) FET
View Answer
Explanation: MOSFET is preferred in digital and analog electronic circuits because it is faster than all other transistors. Also, it has a very high input impedance.
36. Which of the following is true about the depletion layer channel in an NMOS electronic circuit?
a) Inverted change in the channel increases from source to drain
b) Inverted charge remain constant
c) Inverted change in the channel decreases from source to drain
d) Potential in the channel decreases from source to drain
View Answer
Explanation: When the depletion layer starts moving into the channel, due to the reverse bias of drain and substrate voltage, the inverted charge in the channel decreases from source to drain.
37. Which of the following is true about Zener diode?
a) It is lightly doped
b) It is mostly used in voltage regulator electronic circuits
c) It is used in forward bias
d) It has avalanche breakdown
View Answer
Explanation: Zener diode is a heavily doped diode. It is used in reverse bias. It has Zener breakdown. It is used in voltage regulators because it passes an excess amount of current in breakdown mode by maintaining constant voltage across the load.
38. In which region does BJT act as the OFF switch in electronic circuits?
a) Cut-off
b) Saturation
c) Active
d) Reverse saturation
View Answer
Explanation: In the saturation region, the emitter-base junction is forward biased, the collector-base junction is also forward biased. This is the operating mode when no current flows through BJT.
Chapterwise Multiple Choice Questions on Electronic Devices and Circuits
- Electronic Devices and Circuits Overview
- Conduction in Semiconductors
- Semiconductor-Diode Characteristics
- Diodes
- Application of Diodes
- Transistor Characteristics
- Transistor Biasing and Thermal Stabilization
- Signals and Amplifiers
- Operational Amplifiers
- MOS Field Effect Transistors (MOSFETs)
- Bipolar Junction Triodes (BJTs)
- Small-Signal Low-Frequency AC models of Transistors
- Field-Effect Transistors
- Large Signal Amplifiers
- Low Frequency Transistor Amplifier Circuit
- High Frequency Transistor
- Frequency Response
- Differential and Multistage Amplifiers
- Power Amplifiers
1. MCQ on Electronic Devices and Circuits Overview
The section contains Electronic Devices and Circuits multiple choice questions and answers on basics of electronic devices and circuits, methods, frequency responses, time signals, network theorems, analysis of circuits, modulation, transmission and coupled circuits.
2. Electronic Devices and Circuits Multiple Choice Questions on Conduction in Semiconductors
The section contains Electronic Devices and Circuits questions and answers on semiconductor electrons, holes and conductivity, donor and acceptor impurities, fermi level semiconductor, charge densities, diffusion, carrier lifetime, continuity equation and hall effect.
3. Electronic Devices and Circuits MCQ on Semiconductor-Diode Characteristics
The section contains Electronic Devices and Circuits MCQs on pn junction qualitative theory, p-n junction diode, band structure of open circuited p-n junction, components in p-n junction diode, volt ampere characteristics, diode resistance and capacitances, pn diode switching times, breakdown and tunnel diodes, point contact diode, p-i-n diode and its characteristics.
4. Electronic Devices and Circuits Multiple Choice Questions on Diodes
The section contains Electronic Devices and Circuits multiple choice questions and answers on basics of diode, types of diodes which includes zener diode and others, limiting and clamping circuits, rectifiers and characteristics of junction diode and diode forward characteristics modelling.
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5. Electronic Devices and Circuits MCQ on Application of Diodes
The section contains Electronic Devices and Circuits questions and answers on half-wave and full-wave rectifier, bridge and voltmeter rectifier, inductor and capacitor filters, l-section filters, clc filters and voltage regulation.
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6. Electronic Devices and Circuits Multiple Choice Question on Transistor Characteristics
The section contains Electronic Devices and Circuits MCQs on transistor amplifier, transistor construction, junction transistor, common base, emitter and collector configuration, ce and cb characteristics, dc load lines, transistor switch and switching times.
7. Electronic Devices and Circuits MCQ on Transistor Biasing and Thermal Stabilization
The section contains Electronic Devices and Circuits multiple choice questions and answers on operating point, bias stability, collector-to-base and collector-emitter bias, self bias, bias compensation, thermistor, thermal runway and stability.
8. Electronic Devices and Circuits Multiple Choice Questions on Signals and Amplifiers
The section contains Electronic Devices and Circuits questions and answers on basics of signals, amplifiers, sinusoidal steady state analysis, amplifier circuit models and frequency response.
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9. Electronic Devices and Circuits MCQ on Operational Amplifiers
The section contains Electronic Devices and Circuits MCQs on ideal operational amplifiers, inverting and non-inverting configuration, differentiators and differential amplifiers, operational amplifiers, finite open loop gain effect, circuit performance bandwidth and large signal operations.
10. Electronic Devices and Circuits Multiple Choice Questions on MOS Field Effect Transistors (MOSFETs)
The section contains multiple choice questions and answers on basics of MOSFET, device structure, physical and small signal operation of MOSFET, basics of MOSFET configurations and circuit biasing, body effect and discrete MOSFET circuits.
11. Electronic Devices and Circuits MCQ on Bipolar Junction Triodes (BJTs)
The section contains Electronic Devices and Circuits questions and answers on basics of BJT, device structures and physical operations, circuits, current-voltage properties, amplifier design, signal operations and circuit configuration and biasing.
12. Electronic Devices and Circuits Multiple Choice Questions on Small-Signal Low-Frequency AC models of Transistors
The section contains Electronic Devices and Circuits MCQs on ac models and analysis, transistor amplifier, biasing parameters, two port devices and hybrid model, transistor hybrid model, h-parameters and its measurement, cb transistor physical model, hybrid model in ce, cb and cc, ac and dc analysis problems, transistor circuit analysis and millers theorem.
13. Electronic Devices and Circuits MCQ on Field-Effect Transistors
The section contains Electronic Devices and Circuits multiple choice questions and answers on junction field effect transistor, pinch off voltage, insulated gate, fet small signal model, common source and drain amplifier, fet biasing, fet amplifier and unijunction transistors.
14. Electronic Devices and Circuits Multiple Choice Questions on Large Signal Amplifiers
The section contains Electronic Devices and Circuits questions and answers on class a large signal amplifiers, second and higher order harmonic distortion.
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15. Electronic Devices and Circuits MCQ on Low Frequency Transistor Amplifier Circuit
The section contains Electronic Devices and Circuits MCQs on cascading amplifiers, decibel, cc and cb configurations, ce amplifier, emitter follower, high input resistance transistor circuit, cascode transistor and amplifiers.
16. Electronic Devices and Circuits Multiple Choice Questions on High Frequency Transistor
The section contains Electronic Devices and Circuits multiple choice questions and answers on high frequency t model, hybrid pi models, alpha cutoff frequency, ce short circuit current frequency response, resistive load and transistor amplifier response.
17. Electronic Devices and Circuits MCQ on Frequency Response
The section contains Electronic Devices and Circuits questions and answers on low and high frequency responses on cs and ce amplifiers, high frequency models of bjt and mosfet, millers theorem, high frequency response of source and emitter followers, differential amplifiers, mos and bipolar cascode amplifiers, cd-cs, cc-ce, cd-ce, cc-cb and cd-cg configurations, pole splitting, frequency and miller compensation.
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18. Differential and Multistage Amplifiers Multiple Choice Questions
The section contains Electronic Devices and Circuits MCQs on input bias, voltage, current, multistage and differential amplifiers, feedback structure and negative feedback properties, transconductance and transresistance amplifiers, a, b and ab output stages, feedback effects, power bjts, heat sinks and variations in ab classification.
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19. Electronic Devices and Circuits MCQ on Power Amplifiers
The section contains Electronic Devices and Circuits multiple choice questions and answers on oscillators, class b and d amplifiers.
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Wish you the best in your endeavor to learn and master Electronic Devices and Circuits!
