Electrical Engineering Quiz 29

1 / 50

Which of the following primary cells has the highest voltage___________ ?

Carbon-zinc

Mercury

Manganese-alkaline

Lithium

2 / 50

IGBT combines the advantages of_____________?

None of these

BJTs and SITs

SITs and MOSFETs

BJTs and MOSFETs

3 / 50

Superposition theorem can be applied only to circuits having____________?

passive elements

linear bilateral elements

resistive elements

non-linear elements

4 / 50

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

32 A/s

64 A/s

4 A/s

16 A/s

5 / 50

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

increase

remain uncharged

decrease

become zero

6 / 50

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

variable speed motors

low horse power motors

single phase motors

high speed motors

7 / 50

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

Both Zener and avalanche mechanism

None of the above

Avalanche mechanism

Zener mechanism

8 / 50

In case of steam engines the steam pressure is_______________?

1 to 4 kgf/cm2

25 to 35 kgf/cm2

10 to 15 kgf/cm2

5 to 8 kgf/cm2

9 / 50

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

A.C. slip ring motor

Synchronous motor

Single phase motor

Ward-Leonard controlled D.C. shunt motor

10 / 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

11 / 50

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

cut off

VDD

12 / 50

Which semiconductor device acts like a diode and two transistor?

Triac

UJT

SCR

Diac

13 / 50

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

50 MVA

15 MVA

1.5 MVA

5 MVA

14 / 50

The transfer function is applicable to which of the following ?

Linear and time-in variant systems

Linear and time-variant systems

Linear systems

Non-linear systems

15 / 50

With rise in temperature the resistance of semi-conductors_________________?

decreases

remains constant

increases

first increases and then decreases

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 lower than logic 1 voltage level

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

logic 0 voltage level is higher than logic 1 voltage level

17 / 50

Why resistor is used in Snubber circuit_________________ ?

All of these

To minimize the discharging current

To minimize the charging current

To minimize the loss

18 / 50

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

All of the above

Force equation

Magnetic circuit equation

Heating equation

19 / 50

Which of the following is not a source of power?

Solar cell

Photoelectric cell

Thermocouple

Photovoltaic cell

20 / 50

Load center in a power station is___________?

center of coal fields

center of maximum load of equipments

center of gravity of electrical system

None

21 / 50

(1(10101)2 is_______________?

( 69)10

? (5)10

(41 )10

(37)10

22 / 50

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

0 mA

ID(on)

IDSS

maximum

23 / 50

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

31.25 percent of copper

66.7 percent of copper

33.3 percent of copper

125 percent of copper

24 / 50

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

insulation failure

mechanical vibration

impulse voltage

loose connection

25 / 50

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

7.5 MVA

10 MVA

2 MVA

5 MVA

26 / 50

The value of negative feedback fraction is always _______________?

Equal to 1

None of the above

Less than 1

More than 1

27 / 50

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

2.9

2.4

1.5

28 / 50

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

supply voltage is low

load impedance is low

load impedance is high

none of the above

29 / 50

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

none of the above

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

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

30 / 50

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

specific volume

electrical conductivity

resistance per unit length for same cross-section

co-efficient of linear expansion

31 / 50

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

hydraulic turbine

gas turbine

diesel engine

steam turbine

32 / 50

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

is not affected

decreases

increases

depends on Ri

33 / 50

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

Remains the same

Increases

None of the above

Decreases

34 / 50

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

all of the above

ammeter

voltmeter

galvanometer

35 / 50

The typical value of SCR for modern alternator is____________?

1.2.

1.5.

1.0.

0.5.

36 / 50

Unipolar modulation is generally used in____________?

DC ? AC converters

AC ? DC converters

AC ? AC converters

DC ? DC converters

37 / 50

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

poor insulation

Overload

Core saturation

loose connections

38 / 50

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

increase overload capacity

improve power factor

to improve torque

reduce fluctuations in torque

39 / 50

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

all of the above

voltage

duration of contact

current

40 / 50

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

Load break switch

Circuit breakers

Circuit breakers and load break switches

Isolators

41 / 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__________?

0.01

0.02

0.04

0.03

42 / 50

A synchronous motor will always stop when:______________?

excitation winding gets disconnected

supply voltage fluctuates

supply voltage frequency changes

load in motor varies

43 / 50

In a circuit breaker the basic problem is to________________?

extinguish the arc

emit the ionizing electrons

transmit large power

maintain the arc

44 / 50

If temperature changes, h parameters of a transistor ________________?

Also change

Do not change

May or may not change

None

45 / 50

A JFET is also called____________ transistor?

bipolar

none of the above

unijunction

unipolar

46 / 50

Reheat factor in steam turbines depends on______________?

stage efficiency only

exit pressure only

all of the above

initial pressures and temperature only

47 / 50

A MOSFET, for its conduction uses_____________?

Only majority carriers

None of these

Both minority and majority carriers

Only minority carriers

48 / 50

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

none of the above

in increased

is decreased

remains the same

49 / 50

Which of the following properties a damping oil must possess ?

All of the above

Must be a good insulator

Should be non-evaporating

Should not have corrosive action upon the metal of the vane

50 / 50

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

100 n

50 jt

25 JT

5 n

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