Q .
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
E. NA
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Q .
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)
E. NA
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Q .
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
E. NA
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Q . Assertion (A): When a high reverse voltage is applied to a p-n junction the diode breaks down.
Reason (R): High reverse voltage causes Avalanche effect.
A. Both A and R are true and R is correct explanation of A
B. Both A and R are true but R is not a correct explanation of A
C. A is true but R is false
D. A is false but R is true
E. NA
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Q .
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
E. NA
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Q .
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
E. NA
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Q .
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
E. NA
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Q .
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
E. NA
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Q .
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
E. NA
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Q .
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
E. NA
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Q .
Work function is the maximum energy required by the fastest electron at 0 K to escape from the metal surface.
A. True
B. False
C.
D.
E. NA
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Q .
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
E. NA
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Q .
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
E. NA
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Q .
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
E. NA
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Q .
Work function of oxide coated cathode is much lower than that of tungsten cathode.
A. True
B. False
C.
D.
E. NA
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Q .
The most commonly used semiconductor material is
A. silicon
B. germanium
C. mixture of silicon and germanium
D. none of the above
E. NA
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Q .
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
E. NA
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Q . Assertion (A): A p-n junction has high resistance in reverse direction.
Reason (R): When a reverse bias is applied to p-n junction, the width of depletion layer increases.
A. Both A and R are true and R is correct explanation of A
B. Both A and R are true but R is not a correct explanation of A
C. A is true but R is false
D. A is false but R is true
E. NA
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Q .
Secondary emission is always decremental.
A. True
B. False
C.
D.
E. NA
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Q .
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
E. NA
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Q .
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
E. NA
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Q .
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
E. NA
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Q .
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
E. NA
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Q .
Ferrite have
A. low copper loss
B. low eddy current loss
C. low resistivity
D. higher specific gravity compared to iron
E. NA
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Q .
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
E. NA
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Q .
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
E. NA
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Q .
In a bipolar transistor which current is largest
A. collector current
B. base current
C. emitter current
D. base current or emitter current
E. NA
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Q .
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
E. NA
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Q .
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
E. NA
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Q .
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
E. NA
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Q .
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
E. NA
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Q . Assertion (A): The reverse saturation current in a semiconductor diode is 4nA at 20°C and 32 nA at 50°C.
Reason (R): The reverse saturation current in a semiconductor diode doubles for every 10°C rise in temperature.
A. Both A and R are true and R is correct explanation of A
B. Both A and R are true but R is not a correct explanation of A
C. A is true but R is false
D. A is false but R is true
E. NA
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Q .
If a ac for transistor is 0.98 then βac is equal to
A. 51
B. 49
C. 47
D. 45
E. NA
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Q .
An increase in temperature increases the width of depletion layer.
A. True
B. False
C.
D.
E. NA
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Q .
The word enhancement mode is associated with
A. tunnel diode
B. MOSFET
C. JFET
D. photo diode
E. NA
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Q .
The number of doped regions in PIN diode is
A. 1
B. 2
C. 3
D. 1 or 2
E. NA
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Q . Assertion (A): The conductivity of p type semiconductor is higher than that of intrinsic semiconductor.
Reason (R): The addition of donor impurity creates additional energy levels below conduction band.
A. Both A and R are true and R is correct explanation of A
B. Both A and R are true but R is not a correct explanation of A
C. A is true but R is false
D. A is false but R is true
E. NA
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Q .
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)
E. NA
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Q .
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
E. NA
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Q .
The types of carriers in a semiconductor are
A. 1
B. 2
C. 3
D. 4
E. NA
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Q .
In an n channel JFET, the gate is
A. n type
B. p type
C. either n or p
D. partially n & partially p
E. NA
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Q .
At room temperature the current in an intrinsic semiconductor is due to
A. holes
B. electrons
C. ions
D. holes and electrons
E. NA
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Q .
Recombination produces new electron-hole pairs
A. True
B. False
C.
D.
E. NA
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Q .
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
E. NA
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Q .
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
E. NA
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Q .
In which of these is reverse recovery time nearly zero?
A. Zener diode
B. Tunnel diode
C. Schottky diode
D. PIN diode
E. NA
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Q .
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
E. NA
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Q .
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
E. NA