Explore topic-wise MCQs in Testing Subject.

This section includes 657 Mcqs, each offering curated multiple-choice questions to sharpen your Testing Subject knowledge and support exam preparation. Choose a topic below to get started.

1.

If an additional two diodes were used to connect the 1 kW load across a bridge rectifier circuits, utilizing the full secondary of the transformer, how much d.c. power could be delivered using a transformer with the rating of 105 VA?

A. 35 W
B. 60 W
C. 85 W
D. 100 W
Answer» D. 100 W
Discussion
2.

In an insulated gate FET, the polarity of inversion layer is the same as that of

A. minority carriers in source
B. majority carriers in source
C. charge on gate electrode
D. minority carriers in drain
Answer» C. charge on gate electrode
Discussion
3.

Hall effect can be used to find the type of semiconductor.

A. True
B. False
Answer» B. False
Discussion
4.

The conductivity of germanium increases by about 6 percent per degree increase in temperature.

A. True
B. False
Answer» B. False
Discussion
5.

The range of visible light is

A. 300 to 2000
B. 200 - 4000
C. 4000 to 7700
D. more than 10000
Answer» D. more than 10000
Discussion
6.

With increasing temperature, the electrical conductivity of metals

A. increases
B. decreases
C. increases first and then decreases
D. remains unaffected
Answer» C. increases first and then decreases
Discussion
7.

In a bipolar transistor which current is smallest

A. collector current
B. base current
C. emitter current
D. any of the three currents
Answer» C. emitter current
Discussion
8.

The reverse saturation current in a semiconductor diode consists of

A. avalanche current
B. zener current
C. minority carrier current
D. minority carrier current and surface leakage current
Answer» E.
Discussion
9.

The current gain of a transistor is the ratio of

A. emitter current to base current
B. emitter current to collector current
C. collector current to base current
D. collector current to emitter current
Answer» D. collector current to emitter current
Discussion
10.

If a sample of Ge and a sample of Si have the same impurity density are kept at room temperature

A. both will have equal value of resistivity
B. both will have equal - ve of resistivity
C. resistivity of germanium will be higher than that of silicon
D. resistivity of silicon will be higher than of Ge
Answer» E.
Discussion
11.

Which of the following constitutes an active component?

A. Semiconductor device
B. Resistors
C. Capacitors
D. Inductors
Answer» B. Resistors
Discussion
12.

Which of the following characteristics of a silicon p-n junction diode make it suitable for use as ideal diode? It has low saturation current.It has high value of cut in voltage.It can withstand large reverse voltage.When compared with germanium diode, silicon diode shows a lower degree of temperature dependence under reverse conditions. Select the answer using the given below

A. 1 and 2
B. 1, 2, 3, 4
C. 2, 3, 4
D. 1, 3
Answer» C. 2, 3, 4
Discussion
13.

On which of the following effect do thermocouples work?

A. Thomson effect
B. Seeback effect
C. Peltier effect
D. Joule effect
Answer» C. Peltier effect
Discussion
14.

Almost all resistors are made in a monolithic integrated circuit

A. during the entire diffusion
B. while growing the epitaxial layer
C. during the base diffusion
D. during the collector diffusion
Answer» B. while growing the epitaxial layer
Discussion
15.

Figure represents a

A. Esaki diode
B. Triac
C. Varactor
D. Gunn diode
Answer» D. Gunn diode
Discussion
16.

The forbidden energy gap for silicon is

A. 0.12 eV
B. 1.12 eV
C. 0.72 eV
D. 7.2 eV
Answer» C. 0.72 eV
Discussion
17.

In energy band diagram of n type semiconductor, the donor energy level is

A. in valence band
B. in conduction band
C. slightly above valence band
D. slightly below conduction band
Answer» E.
Discussion
18.

For an n-channel JEFT having drain source voltage constant if the gate source voltage is increased (more negative) pinch off would occur for

A. high values of drain current
B. saturation values of drain current
C. zero drain current
D. gate current equal to the drain current
Answer» D. gate current equal to the drain current
Discussion
19.

Which of the following statements regarding two transistor model of p-n-n-p device is correct?

A. It explain only the turn on portion of the device characteristics
B. It explain only the turn off portion of the device characteristics
C. It explain only the negative region portion of the device characteristics
D. It explain all the regions of the device characteristics
Answer» E.
Discussion
20.

The kinetic energy of photoelectrons emitted by a photo sensitive surface depends on

A. intensity of the incident radiation
B. wavelength of the incident radiation
C. surface conditions of the surface
D. angle of incidence of radiation
Answer» C. surface conditions of the surface
Discussion
21.

When reverse bias is applied to a junction diode

A. minority carrier current is increased
B. majority carrier current is increased
C. potential barrier is lowered
D. potential barrier is raised
Answer» E.
Discussion
22.

Which of the following is the ferric electric material?

A. Rochelle salt
B. Barium titanate
C. Potassium dihydrogen phosphate
D. All of the above
Answer» E.
Discussion
23.

In which n type device does p substrate extend upto silicon dioxide layer?

A. JFET
B. Depletion type MOSFET
C. Enhancement type MOSFET
D. Both (b) and (c)
Answer» D. Both (b) and (c)
Discussion
24.

Resistivity of metals is expressed in terms of

A. ohm
B. ohm/cm
C. ohm-cm
D. ohm-cm/ C
Answer» D. ohm-cm/ C
Discussion
25.

Zener diode is invariably used with

A. forward bias
B. reverse bias
C. either (a) or (b)
D. zero bias
Answer» C. either (a) or (b)
Discussion
26.

The relation between plate current and plate voltage of a vacuum diode is called

A. Richardson Dushman equation
B. Langmuir Child law
C. Ohm's law
D. Boltzmann's law
Answer» C. Ohm's law
Discussion
27.

Given that the band gap of cadmium sulphide is 2.5 eV, the maximum photon wavelength, for e--hole pair generation will be

A. 5400 mm
B. 540 mm
C. 5400
D. 540
Answer» D. 540
Discussion
28.

In a N-type semi-conductor, the concentration of minority carriers is mainly depends on

A. the number of acceptor atoms
B. the number of donor atoms
C. the extent of doping
D. the temperature of the material
Answer» E.
Discussion
29.

The maximum rectification efficiency in case of full wave rectifier is

A. 100%
B. 81.2%
C. 66.6%
D. 40.6%
Answer» C. 66.6%
Discussion
30.

For a full wave bridge rectifier supplied with 50 Hz a.c., the lowest ripple frequency will be

A. 50 Hz
B. 100 Hz
C. 200 Hz
D. 400 Hz
Answer» C. 200 Hz
Discussion
31.

If 1 kVA transformer is used for all of the following rectifiers, the d.c. power availability will be least in case of

A. half wave rectifier
B. full wave rectifier
C. bridge rectifier
D. three phase full wave rectifier
Answer» E.
Discussion
32.

When a ferromagnetic substance is magnetised, small changes in dimensions occur. Such a phenomenon is known as

A. magnetic hystresis
B. magnetic expansion
C. magneto striction
D. magneto calorisation
Answer» D. magneto calorisation
Discussion
33.

In which of the following case the rating of the transformer to deliver 100 watts of d.c. power to a load, will be least?

A. Half wave rectifier
B. Full wave rectifier
C. Bridge type full wave rectifier
D. Three phase full wave rectifier
Answer» E.
Discussion
34.

Assertion (A): Hall effect is used to find the type of semiconductor. Reason (R): When a specimen of semiconductor carrying current I lies in a magnetic field the force on electrons and holes is in opposite directions.

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
Discussion
35.

The fT of a BJT is related to its gm, Cp and C as follows.

A. <img src="/_files/images/electronics-and-communication-engineering/electronic-devices-and-circuits/53-375-1.png">
B. <img src="/_files/images/electronics-and-communication-engineering/electronic-devices-and-circuits/53-375-2.png">
C. <img src="/_files/images/electronics-and-communication-engineering/electronic-devices-and-circuits/53-375-3.png">
D. <img src="/_files/images/electronics-and-communication-engineering/electronic-devices-and-circuits/53-375-4.png">
Answer» E.
Discussion
36.

When a p-n junction is forward biased. The width of depletion layer decreases.

A. True
B. False
Answer» B. False
Discussion
37.

The O/P char, of a FET is given in the figure. In which region is the device biased for small signal amplification?

A. <i>AB</i>
B. <i>BC</i>
C. <i>CD</i>
D. <i>BD</i>
Answer» C. <i>CD</i>
Discussion
38.

Photoelectric effect occurs only in semiconductors and not in metals.

A. True
B. False
Answer» C.
Discussion
39.

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
Discussion
40.

Lowest resistivity of the following is

A. constantan
B. german silver
C. manganin
D. nichrome
Answer» C. manganin
Discussion
41.

Peak inverse voltage will be highest for

A. half wave rectifier
B. full wave rectifier
C. bridge rectifier
D. three phase full wave rectifier
Answer» C. bridge rectifier
Discussion
42.

Assertion (A): The reverse current in a p-n junction is nearly constant. Reason (R): The reverse breakdown voltage of a p-n diode depends on the extent of doping.

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
Discussion
43.

Which rectifier has the best ratio of rectification?

A. Half wave rectifier
B. Full wave rectifier
C. Bridge rectifier
D. Three phase full wave rectifier
Answer» E.
Discussion
44.

Assertion (A): A p-n junction is used as rectifier. Reason (R): A p-n junction has low resistance in forward direction and high resistance in reverse direction.

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
Discussion
45.

In an integrated circuit the SiO2 layers provide

A. electrical connection to external Ckt.
B. physical strength
C. isolation
D. conducting path.
Answer» D. conducting path.
Discussion
46.

The output v-i characteristics of enhancement type MOSFET has

A. only an ohmic region
B. only a saturation region
C. an ohmic region at low voltage value and a saturation region at high voltage
D. a saturation region at low voltage value and an ohmic region at high voltage
Answer» D. a saturation region at low voltage value and an ohmic region at high voltage
Discussion
47.

For a n-channel JFET with r0 = 10 kW, (VGs= 0 V, VP = - 6 V)the drain resistance rd at VGS= - 3 V is given by

A. 40 k&ohm;
B. 2.5 k&ohm;
C. 4.44 kW
D. 120 kW
Answer» B. 2.5 k&ohm;
Discussion
48.

Which of the following are voltage controlled devices?

A. Vacum triode
B. FET
C. SCR
D. Both (a) and (b)
Answer» E.
Discussion
49.

In a full wave rectifier, the current in each of the diodes flows for

A. the complete cycle of the input signal
B. half cycle of the input signal
C. less than half cycle of the input signal
D. one-fourth cycle of the input signal
Answer» C. less than half cycle of the input signal
Discussion
50.

In an ideal junction transistor the impurity concentration in emitter (E ), base (B) and collector (C) is such that

A. E > B > C
B. B > C > E
C. C > E > B
D. C = E = B
Answer» B. B > C > E
Discussion