Electrical Engineering Quiz 31

1 / 50

In a JFET, IDSS is known as ________________?

drain to source current with gate shorted

drain to source current with gate open

none of the above

drain to source current

2 / 50

Suri transmission is_________________?

hydro-pneumatic

electrical-pneumatic

mechanical-electrical

hydro-mechanical

3 / 50

When current feedback (negative) is applied to an amplifier, its input impedance _____________?

Is increased

Is decreased

Remains the same

None of the above

4 / 50

In the squirrel-cage induction motor the rotor slots are usually given slight skew__________?

to ensure easy fabrication

to increase the tensile strength of the rotor bars

none of the above

to reduce the magnetic hum and locking tendency of the rotor

5 / 50

Annual depreciation of the plant it proportional to the earning capacity of the plant vide

reducing balances depreciation

sinking fund depreciation

straight line depreciation

none of the above

6 / 50

An induction motor is__________?

self-starting with zero torque

self-starting with high torque

non-self starting

self-starting with low torque

7 / 50

The output power of the cascaded amplifier / attenuator system can be determined using___________?

Actual gain of amplifier

Actual gain of attenuator

Gain in dB of amplifier and attenuator

Actual gain of amplifier and attenuator

8 / 50

Introducing a resistor in the emitter of a common amplifier stabilizes the dc operating point against variations in____________?

Both Temperature & ?

Only the temperature

only the ? of the transistor

None of the above

9 / 50

Reheat factor is the ratio of_____________?

None

isentropic heat drop to useful heat drop

adiabatic heat drop to isentropic heat drop

cumulative actual enthalpy drop for the stages to total is isentropic enthalpy heat drop

10 / 50

Which of the following devices is used for conversion of co-ordinates ?

Microsyn

Selsyn

Synchro-transformer

Synchro-resolver

11 / 50

In arc furnace the function of choke is______________?

to stabilize the arc

none of the above

to imprpve, power factor

to reduce severity of the surge

12 / 50

The time constant of the capacitance circuit is defined as the time during which voltage________?

rises to 63.2% of its final steady value

rises to 38.6% of its final steady value

falls to 36.8% of its final steady value

none of the above

13 / 50

Following D.C. generator will be in a position to build up without any residual magnetism in the poles______________?

shunt generator

series generator

self-excited generator

compound generator

14 / 50

If the power level of an amplifier reduces to half, the db gain will fall by___________?

3 db

2 db

5 db

10 db

15 / 50

Shunt generators are most suited for stable parallel operation because of their______________?

linear voltage characteristics

identical voltage characteristics

drooping voltage characteristics

rising voltage characteristics

16 / 50

In forward blocking mode of a thyristor________?

Junction J1 and J2 is in forward bias and J3 is in reverse bias.

Junction J1, J3 is in reverse bias and J2 is in forward bias.

junction J2 is in reverse bias and J1, J3 is in forward bias.

junction J3 is in forward bias and J1, J2 is in reverse bias.

17 / 50

In an induction motor the relationship between stator slots and rotor slots is that_____________?

stator slots are exact multiple of rotor slots

stator slots are equal to rotor slots

stator slots are not exact multiple of rotor slots

none of the above

18 / 50

Mutually inductance between two magnetically-coupled coils depends on____________?

permeability of the core

all of the above

the number of their turns

cross-sectional area of their common core

19 / 50

No-load current in a transformer________________?

lags behind the voltage by about 75?

leads the voltage by about 15?

lags behind the voltage by about 15?

leads the voltage by about 75?

20 / 50

The latching current of GTO should be of order

100 mA

500 mA

1:00 AM

2:00 AM

21 / 50

Voltage commutation circuit can be converted into a current commutation by interchanging the positions of____________?

Capacitor and load

Diode and capacitor

Inductor and capacitor

Capacitor and SCR

22 / 50

H.R. fuses provide best protection against________________?

overload

short-circuits

reverse current

open-circuits

23 / 50

A voltage divider consists of two 68 k? resistors and a 24 V source. The unknown output voltage is______________?

0 V

12 V

6 V

24 V

24 / 50

The electric charge of 100 ?C is 13cm apart from another charge 16.9?C electric force between them is_____________?

900N

9x106N

9x107N

9x105N

25 / 50

In an induction motor, no-load the slip is generally____________?

less than 1%

1.50%

26 / 50

Mains a.c. power is converrted into d.c. power for_________________?

heaters

using in electronic equipment

lighting purposes

none of the above

27 / 50

As load on an induction motor goes on increasing______________?

its power factor remains constant

its power factor goes on increasing up to full load and then it falls again

its power factor goes on decreasing

its power factor goes on increasing even after full load

28 / 50

Magnetism of a magnet can be destroyed by_____________?

hammering

by inductive action of another magnet

by all above methods

heating

29 / 50

The change of cross-sectional area of conductor in magnetic field will affect______________?

none of the above

reluctance of conductor

resistance of conductor

All

30 / 50

Dry cell is modification of____________?

Leclanche cell

Edison cell

Lead-acid cell

Deniell cell

31 / 50

In a regenerative feed heating cycle, the greatest economy is affected___________?

when steam is extracted only from the last stage of steam turbine

when steam is extracted only from the first stage of steam turbine

when steam is extracted from only one suitable point of steam turbine

when steam is extracted from several places in different stages of steam turbine

32 / 50

Copper, even though costly, finds use in the windings of electrical machines because_____________?

all of the above

None

copper points offer low contact resistance

copper can be easily soldered and welded

33 / 50

Depreciation charges are high in case of__________?

diesel plant

thermal plant

none of these

hydroelectric plant

34 / 50

The rapid wear of brushes takes place due to____________?

all of the above factors

rough commutator bars

abrasion from dust

excessive spring pressure

35 / 50

In constant voltage charging method, the charging current from discharged to fully charged condition_____________?

none of the above

decreases

increases

remains constant

36 / 50

The value of emitter capacitor CE in a multistage amplifier is about____________?

50 ?F

0.01 ?F

1 ?F

100 pF

37 / 50

The advantage of oil filled cables is_________?

smaller overall size

no ionisation, oxidation and formation of voids

all of the above

more perfect impregnation

38 / 50

Digital ICs process______________?

None of the above

Both digital and linear signals

Digital signals only

Linear signals only

39 / 50

An SCR has three terminals viz ________________?

Cathode, anode, gate

Anode, cathode, drain

Anode, cathode, grid

None of the above

40 / 50

Steel wire is used as____________?

overhead telephone wire

earth wire

all of the above

core wire of ACSR

41 / 50

The capacitance between two plates increases with____________?

shorter plate area and shorter distance between them

larger plate area and shorter distance between plates

larger plate area, longer distance between plates and higher,applied voltage

shorter plate area and higher applied voltage

42 / 50

In _________ system fuel from a central pulverizing unit is delivered to a bunker and then to the various burners?

unit

none of the above

All

central

43 / 50

A sinusoidal voltage with a peak-to-peak value of 18 V is applied to an RC low-pass filter. If the reactance at the input frequency is zero, the output voltage is____________?

zero

18 V peak-to-peak

12.74 V peak-to-peak

9 V peak-to-peak

44 / 50

In a resistance furnace the atmosphere is_____________?

reducing

oxidizing

neutral

deoxidising

45 / 50

Low power factor is usually not due to___________?

arc lamps

incandescent lamp

fluorescent tubes

induction motors

46 / 50

A centrifugal switch is used to dis- connect ?starting winding when motor has___________?

picked up about 50 to 70 per cent of rated speed

run for about 1 minute

run for about 5 minutes

picked up about 10 to 25 per cent of rated speed

47 / 50

In coal preparation plant, magnetic separators are used to remove___________?

sand

dust

clinkers

iron particles

48 / 50

A signal other than the reference input that tends to affect the value of controlled variable is known as_________________?

control element

command

disturbance

reference input

49 / 50

Silicon steel used in lamination?s mainly reduces___________?

copper losses

eddy current losses

hysteresis loss

all of the above

50 / 50

Due to which of the following reasons the cables should not be operated too hot ?

Unequal expansion may create voids in the insulation which will lead to ionization

All of the above

The oil may loose its viscosity and it may start drawing off from higher levels

Expansion of the oil may cause the sheath to burst

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