Electronic Devices And Circuits MCQs

Practice and Learn through MCQs and Quizzes. W3Definitions.com have 314 Electronic Devices And Circuits MCQs

A bistable multivibrator

  • A. has no stable state
  • B. has one stable state
  • C. has two stable state
  • D. none of the above
  • Correct Answer: Option C

A diode is operating in forward region and the forward voltage and current are v = 3 + 0.3 sin ωt (volts) and i = 5 + 0.2 sin ωt (mA). The average power dissipated is

  • A. 15 mW
  • B. about 15 mW
  • C. 1.5 mW
  • D. about 1.5 mW
  • Correct Answer: Option B

A FET is to be operated as voltage variable resistor. For this drain to source voltage VDS should be,

  • A. 74
  • B. = VP
  • C. < VP
  • D. > VP
  • Correct Answer: Option C

A JFET

  • A. is current controlled device
  • B. has low input resistance
  • C. has high gate current
  • D. is a voltage controlled device
  • Correct Answer: Option D

A JFET behaves as a constant current source when

  • A. VGS = 0
  • B. VGS is less than pinch off voltage
  • C. VGS = VDS
  • D. VGS is more than pinch off voltage
  • Correct Answer: Option D

A JFET operates in ohmic region when

  • A. VGS = 0
  • B. VGS is less than pinch off voltage
  • C. VGS = is Positive
  • D. VGS = VDS
  • Correct Answer: Option B

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
  • Correct Answer: Option D

A photo diode is

  • A. forward biased
  • B. reverse biased
  • C. either forward or reverse biased
  • D. unbiased
  • Correct Answer: Option B

A reverse voltage of 18 V is applied to a semiconductor diode. The voltage across the depletion layer is

  • A. 0 V
  • B. 0.7 V
  • C. about 10 V
  • D. 18 V
  • Correct Answer: Option D

A sample of N type semiconductor has electron density of 6.25 x 108/cm2 at 300 K. If the intrinsic concentration of carriers in this sample is 2.5 x 1013/cm3 at this temperature, the hole density works out to be

  • A. 106/cm3
  • B. 108/cm3
  • C. 1010/cm3
  • D. 10l2/cm3
  • Correct Answer: Option B

A Schottky diode clamp is used along with switching BJT for

  • A. reducing the power dissipation
  • B. reducing the switching time
  • C. increasing the value of β
  • D. reducing the base current
  • Correct Answer: Option B

A semiconductor diode is biased in forward direction and carrying current I. The current due to holes in p material is

  • A. I
  • C. less than I
  • D. 0.5
  • Correct Answer: Option C

A silicon diode is forward biased and total applied voltage is 5 V. The voltage across p-n junction is

  • A. 5 V
  • B. Slightly less than 5 V
  • C. 0.7 V
  • Correct Answer: Option C

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
  • Correct Answer: Option C

A Varactor diode has

  • A. a fixed capacitance
  • B. a fixed inductance
  • C. a voltage variable capacitance
  • D. a current variable inductance
  • Correct Answer: Option C

A varactor diode is

  • A. reverse biased
  • B. forward biased
  • C. biased to breakdown
  • D. unbiased
  • Correct Answer: Option A

A varactor diode is used for

  • A. tuning
  • B. rectification
  • C. amplification
  • D. rectification and amplification
  • Correct Answer: Option A

A voltage of 9 V is applied in forward direction to a semiconductor diode in series with a load resistance of 1000 Ω. The voltage across the load resistance is zero. It indicates that

  • A. diode is short circuited
  • B. diode is open circuited
  • C. resistor is open circuited
  • D. diode is either o.c or s.c
  • Correct Answer: Option B

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
  • Correct Answer: Option A

AE 139 is a

  • A. tunnel diode
  • B. germanium power transistor
  • C. photoconductive cell
  • D. silicon diode
  • Correct Answer: Option B

An electron rises through a voltage of 100 V. The energy acquired by it will be

  • A. 100 eV
  • B. 100 joules
  • C. (100)1.2 eV
  • D. (100)1.2 joules
  • Correct Answer: Option A

An enhancement mode MOSFET is off when the gate voltage is

  • A. zero
  • B. negative
  • C. less than threshold value
  • D. none of the above
  • Correct Answer: Option C

An enhancement mode MOSFET is on when the gate voltage is

  • A. zero
  • B. positive
  • C. high
  • D. more threshold value
  • Correct Answer: Option D

An extrinsic semiconductor sample has 6 billion silicon atoms and 3 million pentavalent impurity atoms. The number of electrons and holes is

  • A. 3 million each
  • B. 6 billion each
  • C. 3 million free electrons and very small number of holes
  • D. 3 million holes and very small number of free electrons
  • Correct Answer: Option C

An increase in junction temperature of a semiconductor diode

  • A. causes a small increase in reverse saturation current
  • B. causes a large increase in reverse saturation current
  • C. does not affect reverse saturation current
  • D. may cause an increase or decrease in reverse saturation current depending on rating of diode
  • Correct Answer: Option B

An incremental model of a solid state device is one which represents the

  • A. ac property of the device at desired operating point
  • B. dc property of the device at all operating points
  • C. complete ac and dc behaviour at all operating points
  • D. ac property of the device at all operating points
  • Correct Answer: Option A

An intrinsic silicon sample has 1 million free electrons at room temperature. As the temperature is increased

  • A. the number of free electrons increases
  • B. the number of free electrons increases but the number of holes decreases
  • C. the number of free electrons and holes increase by the same amount
  • D. the number of free electrons and holes increase but not by the same amount
  • Correct Answer: Option C

An intrinsic silicon sample has 2 million free electrons. The number of holes in the sample is

  • A. 2 million
  • B. almost zero
  • C. more than 2 million
  • D. less than 2 million
  • Correct Answer: Option A

An LED is

  • A. an ohmic device
  • B. a display device
  • C. a voltage regulated device
  • D. all of the above
  • Correct Answer: Option B

An n channel depletion type MOSFET has

  • A. lightly doped p substrate and highly doped n source and drain
  • B. highly doped p substrate and highly doped n source and drain
  • C. highly doped p substrate and lightly doped n source and drain
  • D. lightly doped n substrate and highly doped n source and drain
  • Correct Answer: Option A

An n channel JFET has IDS whose value is

  • A. maximum for VGS = 0 and minimum for VGS negative and large
  • B. minimum for VGS = 0 and maximum for VGS negative and large
  • C. maximum for VGS = 0 and minimum for VGS positive and large
  • D. minimum for VGS = 0 and maximum for VGS positive and large
  • Correct Answer: Option A

As comparated to an ordinary p-n diode, the extent of impurity atoms in a tunnel diode

  • A. is more
  • B. is less
  • C. may be more or less
  • D. is almost the same
  • Correct Answer: Option A

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
  • Correct Answer: Option C

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)
  • Correct Answer: Option A

As compared to bipolar junction transistor, a FET

  • A. is less noisy
  • B. has better thermal stability
  • C. has higher input resistance
  • D. all of the above
  • Correct Answer: Option D

As temperature increases

  • A. the forbidden energy gap in silicon and germanium increase
  • B. the forbidden energy gap in silicon and germanium decrease
  • C. the forbidden energy gap in silicon decreases while that in germanium decreases
  • D. the forbidden energy gap in silicon increases while that in germanium decreases
  • Correct Answer: Option B

As temperature increases the number of free electrons and holes in an intrinsic semiconductor

  • A. increases
  • B. decreases
  • C. remains the same
  • D. may increase or decrease
  • Correct Answer: Option A

As the reverse voltage is increased, the depletion layer

  • A. becomes narrow
  • B. widens
  • C. remains the same
  • D. reduce to zero
  • Correct Answer: Option B

At 0 K the forbidden energy gap in intrinsic semi conductor is about

  • A. 10 eV
  • B. 6 eV
  • C. 1 eV
  • D. 0.2 eV
  • Correct Answer: Option C

At absolute temperature

  • A. the forbidden energy gap in germanium is higher than that in silicon
  • B. the forbidden energy gap in germanium and silicon are equal
  • C. the forbidden energy gap in silicon is higher than that in germanium
  • D. none of the above
  • Correct Answer: Option C