Electrical Engineering Quiz 29

1 / 50

In case of steam engines the steam pressure is_______________?

1 to 4 kgf/cm2

25 to 35 kgf/cm2

5 to 8 kgf/cm2

10 to 15 kgf/cm2

2 / 50

In a 15 V Zener diode , the breakdown mechanism will occur by ______________?

None of the above

Zener mechanism

Avalanche mechanism

Both Zener and avalanche mechanism

3 / 50

A JFET is also called____________ transistor?

unipolar

none of the above

bipolar

unijunction

4 / 50

Which of the following motors is preferred for boom hoist of a travelling crane ?

Ward-Leonard controlled D.C. shunt motor

Synchronous motor

A.C. slip ring motor

Single phase motor

5 / 50

Load center in a power station is___________?

center of coal fields

center of gravity of electrical system

None

center of maximum load of equipments

6 / 50

As compared to a 2-wire D.C. distributor, a 3-wire distributor with same maximum voltage to earth uses only__________________?

125 percent of copper

66.7 percent of copper

31.25 percent of copper

33.3 percent of copper

7 / 50

For VGS = 0 V, the drain current becomes constant when VDS exceeds ________________?

cut off

VDD

8 / 50

An e.m.f. of 16 volts is induced in a coil of inductance 4H. The rate of change of current must be______________?

64 A/s

4 A/s

32 A/s

16 A/s

9 / 50

Which of the following primary cells has the highest voltage___________ ?

Carbon-zinc

Lithium

Manganese-alkaline

Mercury

10 / 50

A battery of 6 cells will show a drop of _______ volts from fully charged state to fully discharged state

2.4

2.9

1.5

11 / 50

Which of the following works on torque on the current carrying conductor placed in magnetic field ?

voltmeter

galvanometer

all of the above

ammeter

12 / 50

With rise in temperature the resistance of semi-conductors_________________?

first increases and then decreases

decreases

increases

remains constant

13 / 50

If the doping level in a crystal diode is increased, the width of depletion layer_____________?

remains the same

in increased

is decreased

none of the above

14 / 50

(1(10101)2 is_______________?

( 69)10

(41 )10

? (5)10

(37)10

15 / 50

Superposition theorem can be applied only to circuits having____________?

passive elements

non-linear elements

linear bilateral elements

resistive elements

16 / 50

Positive logic in a logic circuit is one in which______________?

logic 0 and 1 are represented by 0 and positive voltage respectively

logic 0 voltage level is higher than logic 1 voltage level

logic 0 voltage level is lower than logic 1 voltage level

logic 0 and, -1 are represented by negative and positive voltages respectively

17 / 50

A synchronous motor will always stop when:______________?

excitation winding gets disconnected

supply voltage frequency changes

supply voltage fluctuates

load in motor varies

18 / 50

The value of negative feedback fraction is always _______________?

More than 1

Equal to 1

Less than 1

None of the above

19 / 50

Which of the following is the most likely source of harmonics in a transformer ?

poor insulation

Core saturation

loose connections

Overload

20 / 50

In a power or distribution transformer about 10 per cent end turns are heavily insulated__________?

to withstand the high voltage drop due to line surge produced by the shunting capacitance of the end turns

to absorb the line surge voltage and save the winding of transformer from damage

none of the above

to reflect the line surge and save the winding of a transformer from damage

21 / 50

For aluminium, as compared to copper, all the following factors have higher values except:

resistance per unit length for same cross-section

co-efficient of linear expansion

specific volume

electrical conductivity

22 / 50

A MOSFET, for its conduction uses_____________?

None of these

Only majority carriers

Both minority and majority carriers

Only minority carriers

23 / 50

Which of the following is not a source of power?

Thermocouple

Solar cell

Photovoltaic cell

Photoelectric cell

24 / 50

N atural air coo ling is generally restricted for transformers up to__________?

1.5 MVA

50 MVA

15 MVA

5 MVA

25 / 50

Reheat factor in steam turbines depends on______________?

exit pressure only

stage efficiency only

initial pressures and temperature only

all of the above

26 / 50

The typical value of SCR for modern alternator is____________?

1.2.

1.5.

0.5.

1.0.

27 / 50

An alternator coupled to a __________ runs at slow speed, as compared to as compared to others.

hydraulic turbine

steam turbine

gas turbine

diesel engine

28 / 50

IGBT combines the advantages of_____________?

BJTs and SITs

BJTs and MOSFETs

None of these

SITs and MOSFETs

29 / 50

Why resistor is used in Snubber circuit_________________ ?

To minimize the discharging current

All of these

To minimize the loss

To minimize the charging current

30 / 50

Which of the following properties a damping oil must possess ?

Must be a good insulator

All of the above

Should be non-evaporating

Should not have corrosive action upon the metal of the vane

31 / 50

As the doping to a pure semiconductor increases, the bulk resistance of the semiconductor_______________?

None of the above

Remains the same

Increases

Decreases

32 / 50

Transformers with a capacity of up to __________ have a cooling radiator system with natural cooling?

5 MVA

7.5 MVA

10 MVA

2 MVA

33 / 50

Which semiconductor device acts like a diode and two transistor?

UJT

SCR

Triac

Diac

34 / 50

Star-delta starting of motors is not possible in case of____________?

variable speed motors

single phase motors

low horse power motors

high speed motors

35 / 50

A certain p-channel E-MOSFET has VGS(th) = -2V. If VGS= 0V, the drain current is ____________?

IDSS

ID(on)

maximum

0 mA

36 / 50

The design of electromagnets is based upon which of the following fundamental equations ?

Magnetic circuit equation

All of the above

Heating equation

Force equation

37 / 50

The short circuit in any winding of the transformer is the result of_______________?

insulation failure

impulse voltage

mechanical vibration

loose connection

38 / 50

Kirchhoff s voltage law applies to circuits with____________?

linear, non-linear, active, passive, time varying as wells as time-in-variant elements

linear elements only

nonlinear elements only

linear, non-linear, active and passive elements

39 / 50

A sine wave has a frequency of 50 Hz. Its angular frequency is ________ radian/second.

5 n

25 JT

100 n

50 jt

40 / 50

A 500 kW, 3-phase, 440 volts, 50 Hz, A.C. induction motor has a speed of 960 r.p.m. on full load. The machine has 6 poles. The slip of the machine will be__________?

0.04

0.01

0.02

0.03

41 / 50

The transfer function is applicable to which of the following ?

Linear and time-variant systems

Linear and time-in variant systems

Linear systems

Non-linear systems

42 / 50

Unipolar modulation is generally used in____________?

AC ? DC converters

AC ? AC converters

DC ? AC converters

DC ? DC converters

43 / 50

The pressure coil of a wattmeter should be connected on the supply side of the current coil when______________?

none of the above

load impedance is high

load impedance is low

supply voltage is low

44 / 50

When a dielectric slab is introduced in a parallel plate capacitor, the potential difference between plates will______________?

remain uncharged

decrease

become zero

increase

45 / 50

The effect of electric shock on human body depends on which of the following?

current

all of the above

duration of contact

voltage

46 / 50

If the feedback resistor in Q15 (above question) is open, the voltage gain ____________?

is not affected

decreases

increases

depends on Ri

47 / 50

For which of the following equipment current rating is not necessary?

Isolators

Circuit breakers

Circuit breakers and load break switches

Load break switch

48 / 50

In a circuit breaker the basic problem is to________________?

transmit large power

emit the ionizing electrons

maintain the arc

extinguish the arc

49 / 50

In a capacitor start and run motors the function of the running capacitor in series with the auxiliary winding is to_______________?

to improve torque

increase overload capacity

reduce fluctuations in torque

improve power factor

50 / 50

If temperature changes, h parameters of a transistor ________________?

None

May or may not change

Do not change

Also change

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