MCQOPTIONS
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MCQOPTIONS
This section includes 1017 Mcqs, each offering curated multiple-choice questions to sharpen your Electronics & Communication Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 951. |
If aac for transistor is 0.98 then βac is equal to |
| A. | 51 |
| B. | 49 |
| C. | 47 |
| D. | 45 |
| Answer» C. 47 | |
| 952. |
As the temperature of an intrinsic semiconductor material is increased |
| A. | protons get excited |
| B. | neutrons acquire charge |
| C. | energy of the atom is increased |
| D. | additional holes are created in the conduction band |
| Answer» D. additional holes are created in the conduction band | |
| 953. |
Piezoelectric materials serves as a source of |
| A. | microwaves |
| B. | ultrasonic waves |
| C. | musical waves |
| D. | resonant waves |
| Answer» C. musical waves | |
| 954. |
Maximum rectification efficiency for a half wave rectifier is |
| A. | 1 |
| B. | 0.88 |
| C. | 0.5 |
| D. | 0.406 |
| Answer» E. | |
| 955. |
If the atomic number of germanium is 32, the number of electrons in the outer most shell will be |
| A. | 2 |
| B. | 3 |
| C. | 4 |
| D. | 6 |
| Answer» D. 6 | |
| 956. |
If the temperature of on extrinsic semiconductor is increased so that the intrinsic carrier concentration is doubled, then |
| A. | the majority carrier density doubles |
| B. | the minority carrier density doubles |
| C. | the minority carrier density becomes 4 times the original value |
| D. | both majority and minority carrier densities double |
| Answer» E. | |
| 957. |
A Varactor diode has |
| A. | a fixed capacitance |
| B. | a fixed inductance |
| C. | a voltage variable capacitance |
| D. | a current variable inductance |
| Answer» D. a current variable inductance | |
| 958. |
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 |
| Answer» D. Both holes and electrons are produced | |
| 959. |
In CE configuration, the output characteristics of a bipolar junction transistor is drawn between |
| A. | IC and VCB |
| B. | IE and VCB |
| C. | IC and VCE |
| D. | IE and VCE |
| Answer» D. IE and VCE | |
| 960. |
The maximum rectification efficiency in case of full wave rectifier is |
| A. | 1 |
| B. | 0.812 |
| C. | 0.666 |
| D. | 0.406 |
| Answer» C. 0.666 | |
| 961. |
How is an N-channel junction Field Effect Transistor operated as an amplifier? |
| A. | With a forward bias gate source junction |
| B. | With a reverse bias gate-source junction |
| C. | With a open gate source junction |
| D. | With a shorted gate source junction |
| Answer» C. With a open gate source junction | |
| 962. |
Consider the following statements about diamagnetic material and diamagnetism. The materials have negative magnetic susceptibility.At very low temperature diamagnetic materials. Which of the statements given above is/are correct? |
| A. | 1 only |
| B. | 2 only |
| C. | Both 1 and 2 |
| D. | neither 1 nor 2 |
| Answer» B. 2 only | |
| 963. |
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 |
| Answer» B. 32 V | |
| 964. |
Assertion (A): In CE connection of n-p-n transistor. VCE is positive. Reason (R): In BJT, the base collector junction is reverse biased. |
| 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 |
| Answer» B. Both A and R are true but R is not a correct explanation of A | |
| 965. |
Gold is often diffused into silicon P-N junction devices to |
| A. | increase recombination rate |
| B. | reduce recombination rate |
| C. | make silicon a direct gap semiconductor |
| D. | make silicon semimetal |
| Answer» C. make silicon a direct gap semiconductor | |
| 966. |
Dielectric strength of polythene is around |
| A. | 10 kV/mm |
| B. | 40 kV/mm |
| C. | 100 kV/mm |
| D. | 140 kV/mm |
| Answer» C. 100 kV/mm | |
| 967. |
Assertion (A): Intrinsic semiconductor is an insulator at 0 K. Reason (R): Fermi level in intrinsic semiconductor is in the centre of forbidden energy 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 |
| Answer» B. Both A and R are true but R is not a correct explanation of A | |
| 968. |
The drift velocity of electrons and holes is proportional to electric field strength. |
| A. | 1 |
| B. | |
| Answer» B. | |
| 969. |
Which statement is false as regards holes |
| A. | Holes exist in conductors as well as semiconductors |
| B. | Holes constitute positive charges |
| C. | Holes exist only in semiconductors |
| D. | Holes and electrons recombine |
| Answer» B. Holes constitute positive charges | |
| 970. |
A particular green LED emits light of wavelength 5490, √Ö, 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 |
| Answer» B. 1.98 eV | |
| 971. |
Assertion (A): The conductivity of an n type semiconductor increases with increase in temperature and increase in density of donor atoms. Reason (R): Diffusion of carriers occurs in semiconductors. |
| 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 |
| Answer» C. A is true but R is false | |
| 972. |
To ensure that a zener diode does not get destroyed |
| A. | the applied voltage should not exceed breakdown voltage |
| B. | the current should not exceed rated current |
| C. | the current should be less than magnitude of barrier potential |
| D. | both (a) and (b) |
| Answer» C. the current should be less than magnitude of barrier potential | |
| 973. |
If E is energy level of electron and EF is Fermi level, then |
| A. | all quantum states with E less than EF will be occupied at T = 0 |
| B. | all quantum states with E less than EF will be empty at T = 0 |
| C. | some quantum states with E less than EF will be occupied at T = 0 |
| D. | none of the above |
| Answer» B. all quantum states with E less than EF will be empty at T = 0 | |
| 974. |
Under low level injection assumption, the infected minority carrier current for an extrinsic semiconductor is essentially the |
| A. | diffusion current |
| B. | drift current |
| C. | recombination current |
| D. | induced current |
| Answer» B. drift current | |
| 975. |
Assertion (A): In p-n-p transistor collector current is termed negative. Reason (R): In p-n-p transistor holes are majority carriers. |
| 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 |
| Answer» C. A is true but R is false | |
| 976. |
For an P-channel enhancement type MOSFET determine the drain current if K = 0.278 x 10-3A/V2, VGS = -4V, VT = -2V, Voltage equivalent at 27°C = 26 mV. |
| A. | 10 mA |
| B. | 1.11 mA |
| C. | 0.751 mA |
| D. | 46.98 mA |
| Answer» C. 0.751 mA | |
| 977. |
The temperature of cathode is increased from 2500K to 2600K. The increase in thermionic emission current is about |
| A. | 0.001 |
| B. | 0.04 |
| C. | 0.5 |
| D. | 1.5 |
| Answer» E. | |
| 978. |
Which of the following material can be used in cable shields? |
| A. | Copper |
| B. | Aluminium |
| C. | Cast iron |
| D. | Lead |
| Answer» E. | |
| 979. |
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 |
| Answer» B. Both A and R are true but R is not a correct explanation of A | |
| 980. |
As temperature increases the forbidden gap in silicon increases. |
| A. | 1 |
| B. | |
| C. | Both A and R are true and R is correct explanation of A |
| D. | Both A and R are true but R is not a correct explanation of A |
| Answer» C. Both A and R are true and R is correct explanation of A | |
| 981. |
In n type semiconductor, the free electron concentration |
| A. | is nearly equal to density of donor atoms |
| B. | is much greater than density of donor atoms |
| C. | is much less than density of donor atoms |
| D. | may be equal to or more or less than density of donor atoms |
| Answer» B. is much greater than density of donor atoms | |
| 982. |
Figure shows the terminals of a transistor in plastic package TO 18. Then |
| A. | terminals 1, 2, 3 are emitter, collector, base respectively |
| B. | terminals 1, 2, 3 are emitter, base, collector respectively |
| C. | terminals 1, 2, 3 are base, emitter collector, respectively |
| D. | terminals 1, 2, 3 are collector, emitter, base respectively |
| Answer» C. terminals 1, 2, 3 are base, emitter collector, respectively | |
| 983. |
Figure represents a |
| A. | Esaki diode |
| B. | Triac |
| C. | Varactor |
| D. | Gunn diode |
| Answer» D. Gunn diode | |
| 984. |
The threshold voltage of an n-channel enhancement mode MOSFET is 0.5 when the device is biased at a gate voltage of 3V. Pinch off would occur at a drain voltage of |
| A. | 1.5 V |
| B. | 2.5 V |
| C. | 3.5 V |
| D. | 4.5 V |
| Answer» C. 3.5 V | |
| 985. |
The effect of a finite gain of operational amplifier used in an integrator is that |
| A. | it would not integrator |
| B. | slope of the O/P will varied with time |
| C. | final value of the O/P |
| D. | there will be instability in the cirucuit |
| Answer» C. final value of the O/P | |
| 986. |
In a JFET VDS exceeds the rated value. Then it operates in |
| A. | active region |
| B. | ohmic region |
| C. | cut off region |
| D. | either cut off or active region |
| Answer» D. either cut off or active region | |
| 987. |
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 |
| Answer» B. holes | |
| 988. |
Which of these has peak and valley points in v-i curve? |
| A. | Tunnel diode |
| B. | Zener diode |
| C. | PIN diode |
| D. | Schottky diode |
| Answer» B. Zener diode | |
| 989. |
A 2 bit binary multiplier can be implemented using |
| A. | 2 I/P only |
| B. | 2 I/P XORs and 4 I/P and gates only |
| C. | two 2 I/Ps NOR and one XNOR gate |
| D. | XOR gates and shift Register |
| Answer» C. two 2 I/Ps NOR and one XNOR gate | |
| 990. |
Which of these has 3 layers? |
| A. | PIN diode |
| B. | Zener diode |
| C. | Schottky diode |
| D. | Photo diode |
| Answer» B. Zener diode | |
| 991. |
At a P-N junction, the potential barrier is due to the charges on either side of the junction, which consists of |
| A. | fixed donor and acceptor ions |
| B. | majority carriers only |
| C. | minority carriers only |
| D. | both majority and minority carriers |
| Answer» B. majority carriers only | |
| 992. |
The depletion layer in a reverse biased p-n junction is due to the presence of |
| A. | electrons |
| B. | holes |
| C. | both electrons and holes |
| D. | immobile ions |
| Answer» E. | |
| 993. |
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 |
| Answer» E. | |
| 994. |
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 |
| Answer» C. VGS = is Positive | |
| 995. |
Secondary emission is always decremental. |
| A. | 1 |
| B. | |
| C. | is in valence band |
| D. | is in conduction band |
| Answer» C. is in valence band | |
| 996. |
A Darlington emitter follower circuit is some times used in the output stage of a TTL gate in order to |
| A. | increase its IQL |
| B. | reduce its I0H |
| C. | increase its speed of operation |
| D. | reduce power dissipation |
| Answer» D. reduce power dissipation | |
| 997. |
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 |
| Answer» E. | |
| 998. |
Work function is the maximum energy required by the fastest electron at 0 K to escape from the metal surface. |
| A. | 1 |
| B. | |
| Answer» C. | |
| 999. |
Lowest resistivity of the following is |
| A. | constantan |
| B. | german silver |
| C. | manganin |
| D. | nichrome |
| Answer» C. manganin | |
| 1000. |
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 |
| Answer» C. impurity ionization dominants over band to band transition | |