Electronic Devices and Circuits MCQs : This section focuses on the "Electronic Devices and Circuits". These Multiple Choice Questions (MCQs) should be practiced to improve the Electronic Devices and Circuits skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.
Question 1
A p-n junction diode has
A. low forward and high reverse resistance
B. a non-linear v-i characteristics
C. zero forward current till the forward voltage reaches cut in value
D. all of the above
Question 2
In a zener diode
A. the forward current is very high
B. sharp breakdown occurs at a certain reverse voltage
C. the ratio v-i can be negative
D. there are two p-n junctions
Question 3
The number of doped regions in PIN diode is
A. 1
B. 2
C. 3
D. 1 or 2
Question 4
An increase in temperature increases the width of depletion layer.
A. TRUE
B. FALSE
Question 5
Calculate the stability factor and change in IC from 25°C to 100°C for, β = 50, RB/ RE = 250, ΔIC0 = 19.9 nA for emitter bias configuration.
A. 42.53, 0.85 μA
B. 40.91, 0.58 μA
C. 40.91, 0.58 μA
D. 41.10, 0.39 μA
Question 6
Work function of oxide coated cathode is much lower than that of tungsten cathode.
A. TRUE
B. FALSE
Question 7
The normal operation of JFET is
A. constant voltage region
B. constant current region
C. both constant voltage and constant current regions
D. either constant voltage or constant current region
Question 8
In an n channel JFET, the gate is
A. n type
B. p type
C. either n or p
D. partially n & partially p
Question 9
Ferrite have
A. low copper loss
B. low eddy current loss
C. low resistivity
D. higher specific gravity compared to iron
Question 10
In a degenerate n type semiconductor material, the Fermi level,
A. is in valence band
B. is in conduction band
C. is at the centre in between valence and conduction bands
D. is very near valence band
Question 11
As compared to an ordinary semiconductor diode, a Schottky diode
A. has lower cut in voltage
B. has higher cut in voltage
C. lower reverse saturation current
D. both (b) and (c)
Question 12
An LED has a rating of 2 V and 10 mA. It is used along with 6V battery. The range of series resistance is
A. 0 to 200 Ω
B. 200 - 400 Ω
C. 200 Ω and above
D. 400 Ω and above
Question 13
A particular green LED emits light of wavelength 5490, Å, the energy bandgap of the semiconductor material used there is .. h = 6.6 x 10-34 J sec.
A. 2.26 eV
B. 1.98 eV
C. 1.17 eV
D. 0.74 eV
Question 14
Which of the following is true as regards photo emission?
A. Velocity of emitted electrons is dependent on light intensity
B. Rate of photo emission is inversely proportional to light intensity
C. Maximum velocity of electron increases with decreasing wave length
D. Both holes and electrons are produced
Question 15
In a p type material the Fermi level is 0.3 eV above valence band. The concentration of acceptor atoms is increased. The new position of Fermi level is likely to be
A. 0.5 eV above valence band
B. 0.28 eV above valence band
C. 0.1 eV above valence band
D. below the valence band
Question 16
A periodic voltage has following value for equal time intervals changing suddenly from one value to next... 0, 5, 10, 20, 50, 60, 50, 20, 10, 5, 0, -5, -10 etc. Then rms value of the waveform is
A. 31 V
B. 32 V
C. insufficient data
D. none of these
Question 17
Work function is the maximum energy required by the fastest electron at 0 K to escape from the metal surface.
A. TRUE
B. FALSE
Question 18
If aac for transistor is 0.98 then βac is equal to
A. 51
B. 49
C. 47
D. 45
Question 19
A zener diode is used in
A. voltage regulator circuit
B. amplifier circuits
C. both voltage regulator and amplifier circuit
D. none of the above
Question 20
The word enhancement mode is associated with
A. tunnel diode
B. MOSFET
C. JFET
D. photo diode
Question 21
In p-n-p transistor the current IE has two components viz. IEP due to injection of holes from p-region to n-region and IE due to injection of electrons from n-region to p-region. Then
A. IEp and IEn are almost equal
B. IEp >> IEn
C. IEn >> IEp
D. either (a) or (c)
Question 22
The types of carriers in a semiconductor are
A. 1
B. 2
C. 3
D. 4
Question 23
A transistor has two p-n junctions. The batteries should be connected such that
A. both junctions are forward biased
B. both junctions are reverse biased
C. one junction is forward biased and the other is reverse biased
D. none of the above
Question 24
Crossover distortion behaviour is characteristic of
A. class A O/P stage
B. class B O/P stage
C. class AB output stage
D. common pulse O/P state
Question 25
As compared to an ordinary semiconductor diode, a Schottky diode
A. has higher reverse saturation current
B. has higher reverse saturation current and higher cut in voltage
C. has higher reverse saturation current and lower cut in voltage
D. has lower reverse saturation current and lower cut in voltage
Question 26
Secondary emission is always decremental.
A. TRUE
B. FALSE
Question 27
In a bipolar transistor the barrier potential
A. 0
B. a total of 0.7 V
C. 0.7 V across each depletion layer
D. 0.35 V
Question 28
In a bipolar transistor which current is largest
A. collector current
B. base current
C. emitter current
D. base current or emitter current
Question 29
In an n-p-n transistor, the majority carriers in the base are
A. electrons
B. holes
C. both holes and electrons
D. either holes or electrons
Question 30
The most commonly used semiconductor material is
A. silicon
B. germanium
C. mixture of silicon and germanium
D. none of the above
Question 31
In which region of a CE bipolar transistor is collector current almost constant?
A. Saturation region
B. Active region
C. Breakdown region
D. Both saturation and active region
Question 32
An amplifier without feedback has a voltage gain of 50, input resistance of 1 kΩ and output resistance of 2.5 kΩ. The input resistance of the current shunt -ve feedback amplifier using the above amplifier with a feedback factor of 0.2 is
A. 1/11 kΩ
B. 1/5 kΩ
C. 5 kW
D. 11 kW
Question 33
Recombination produces new electron-hole pairs
A. TRUE
B. FALSE
Question 34
A silicon (PN) junction at a temperature of 20°C has a reverse saturation current of 10 pico Ampere. The reverse saturation current at 40°C for the same bias is approximately.
A. 30 pA
B. 40 pA
C. 50 pA
D. 60 pA
Question 35
The amount of photoelectric emission current depends on
A. frequency of incident radiation
B. intensity of incident radiation
C. both frequency and intensity of incident radiation
D. none of the above
Question 36
The power dissipation in a transistor is the product of
A. emitter current and emitter to base voltage
B. emitter current and collector to emitter voltage
C. collector current and collector to emitter voltage
D. none of the above
Question 37
A transistor has a current gain of 0.99 in the CB mode. Its current gain in the CC mode is
A. 100
B. 99
C. 1.01
D. 0.99
Question 38
When a voltage is applied to a semiconductor crystal then the free electrons will flow.
A. towards positive terminal
B. towards negative terminal
C. either towards positive terminal or negative terminal
D. towards positive terminal for 1 μs and towards negative terminal for next 1 μs
Question 39
At very high temperatures the extrinsic semi conductors become intrinsic because
A. drive in diffusion of dopants and carriers
B. band to band transition dominants over impurity ionization
C. impurity ionization dominants over band to band transition
D. band to band transition is balanced by impurity ionization
Question 40
In an n-p-n transistor biased for operation in forward active region
A. emitter is positive with respect to base
B. collector is positive with respect to base
C. base is positive with respect to emitter and collector is positive with respect to base
D. none of the above
Question 41
In which of these is reverse recovery time nearly zero?
A. Zener diode
B. Tunnel diode
C. Schottky diode
D. PIN diode
Question 42
At room temperature the current in an intrinsic semiconductor is due to
A. holes
B. electrons
C. ions
D. holes and electrons
Question 43
The minority carrier life time and diffusion constant in a semiconductor material are respectively 100 microsecond and 100 cm2/sec. The diffusion length is
A. 0.1 cm
B. 0.01 cm
C. 0.0141 cm
D. 1 cm
Question 44
A potential of 7 V is applied to a silicon diode. A resistance of 1 K ohm is also in series with the diode. The current is
A. 7 mA
B. 6.3 mA
C. 0.7 mA
D. 0