# 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

• A. 15 mW
• C. 1.5 mW

• A. 74
• B. = VP
• C. < VP
• D. > VP

## A JFET

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

## 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

## 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

## 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

## A photo diode is

• A. forward biased
• B. reverse biased
• C. either forward or reverse biased
• D. unbiased

• A. 0 V
• B. 0.7 V
• D. 18 V

• A. 106/cm3
• B. 108/cm3
• C. 1010/cm3
• D. 10l2/cm3

## 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

## 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

## 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

## 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

## A Varactor diode has

• A. a fixed capacitance
• B. a fixed inductance
• C. a voltage variable capacitance
• D. a current variable inductance

## A varactor diode is

• A. reverse biased
• B. forward biased
• C. biased to breakdown
• D. unbiased

## A varactor diode is used for

• A. tuning
• B. rectification
• C. amplification
• D. rectification and amplification

## 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

## 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

## AE 139 is a

• A. tunnel diode
• B. germanium power transistor
• C. photoconductive cell
• D. silicon diode

## 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

## 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

## An enhancement mode MOSFET is on when the gate voltage is

• A. zero
• B. positive
• C. high
• D. more threshold value

## 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

## 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

## 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

## 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

## 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

## An LED is

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

## 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

## 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

## 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

## 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

## 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)

## 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

## 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

## 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

## As the reverse voltage is increased, the depletion layer

• A. becomes narrow
• B. widens
• C. remains the same
• D. reduce to zero

• A. 10 eV
• B. 6 eV
• C. 1 eV
• D. 0.2 eV