Electrical Engineering Quiz 65

1 / 50

The change in flux linkages can be caused in which of the following ways ?

The flux is constant with respect to time and is stationary and the coil moves through it

All of the above

The coil is stationary with respect to flux and the flux varies in magnitude with respect to time

Both the changes mentioned above occur together, i.e., the coil moves through a time varying field

2 / 50

If the gain of the critical damped system is increased it will behave as______________?

oscillatory

overdamped

critically damped

underdamped

3 / 50

Which of the following statements is incorrect ?

A capacitor can store charge because it has a dielectric between two conductors

Capacitors in series provide less capacitance but a higher voltage breakdown rating for the combination

The thinner the dielectric, the more the capacitance and the lower the voltage breakdown rating for a capacitor .

A six dot mica capacitor colour coded white, green, black, red and yellow has the capacitance value of 500 pF

4 / 50

Which of the following is reversible in action ?

Motor generator set

Rotary converter

Motor converter

Any of the above

5 / 50

When the stator windings are connected in such a fashion that the number of poles are made half, the speed of the rotor of a synchronous motor___________?

decreases to half the original value

increases to two times the original value

remains same as the original value

tends to becomes zero

6 / 50

When a bogie negotiates a curve, reduction in adhesion occurs resulting in sliding. Thus sliding is acute when_______________?

wheel base of axles is more

none of the above

All

degree of curvature is more

7 / 50

If a D.C. motor designed for 40?C ambient temperature is to be used for 50?C ambient temperature, then the motor_____________?

of higher H.P. should be selected

is to be derated by a factor recommended by manufacturer and select the next higher H.P. motor

of lower H.P. should be selected

can be used for 50?C ambient temperature also

8 / 50

Insulating materials have the function of___________?

conducting very large currents

storing very high currents

preventing an open circuit between the voltage source and the load

preventing a short circuit between conducting wires

9 / 50

A transistor is a___________operated device?

both voltage and current

none of the above

current

voltage

10 / 50

With feed back ____________ reduces?

none of the above

system stability and gain

system gain

system stability

11 / 50

A voltage divider consists of two 100 k? resistors and a 12 V source. What will the output voltage be if a load resistor of 1 M? is connected to the output?

0.57 V

5.7 V

12 V

6 V

12 / 50

In a superhetrodyne receiver, the difference frequency is chosen as the IF rather than the sum frequency because _________________?

The difference frequency is closer to oscillator frequency

None of the above

Lower frequencies are easier to amplify

Only the difference frequency can be modulated

13 / 50

For the same cylinder dimensions and speed, which of the following engine will produce least power?

Diesel engine

All of the above engines will equal power

Petrol engine

Supercharged engine

14 / 50

A steam power station requires space______________?

None

equal to diesel power station

less than diesel power station

more than diesel power station

15 / 50

Which of the following can be measured by LVDT ?

Acceleration

Any of the above

Velocity

Displacement

16 / 50

Induction type single phase energy meters measure electric energy in_______________?

kWh

VAR

17 / 50

Excessive charging a battery tends to____________?

to corrode the positive plates into lead peroxide thereby weakening them physically

produce gassing

increase the internal resistance of the battery

bring about all above changes

18 / 50

The demagnetising component of armature reaction in a D.C. generator___________?

reduces interpoles flux density

increases armature speed

results in sparking trouble

reduces generator e.m.f.

19 / 50

The voltage of domestic supply is 220V. This figure represents__________?

peak value

r.m.s. value

mean value

average value

20 / 50

The fuel used in nuclear reactor is_____________?

uranium

radium

all of the above

cadmium

21 / 50

Six resistors are in parallel. The two lowest-value resistors are both 1.2 k?. The total resistance_____________?

is greater than 1.2 k?

is less than 1.2 k?

is less than 6 k?

is less than 600 ?

22 / 50

The value of starting capacitor of a fractional horse power motor will be__________?

100 uF

400 uF

200 uF

300 uF

23 / 50

The active materials of a nickel-iron battery are___________?

21% solution of KOH

powdered iron and its oxide

nickel hydroxide

all of the above

24 / 50

The cold rolled grain oriented steel has ___________ permeability in the direction of the grain orientation?

minimum

nil

maximum

none of the above

25 / 50

The barrier voltage at a pn junction for germanium is about________________?

Zero

0.3 V

5 V

3 V

26 / 50

Which D.C. motor will be suitable along with flywheel for intermittent light and heavy loads?

Differentially compounded motor

Series motor

Cumulatively compounded motor

Shunt motor

27 / 50

Electric displacement is a__________quantity

both of the above

scalar

none of the above

vector

28 / 50

The product of apparent power and cosine of the phase angle between circuit voltage and current is

volt-amperes

reactive power

true power

instantaneous power

29 / 50

As the breakdown voltage reached, the DIAC exhibits?

All of these

Goes into avalanche condition

Voltage drop snaps back

Negative resistance characteristics

30 / 50

Which of the following are the constants of the transmission lines ?

Capacitance

All of the above

Resistance

Inductance

31 / 50

Ripple factor is the ratio of______________________?

Average value of the ac component of load voltage to the peak value of voltage

Average value of the dc component of load voltage to the ac voltage

Peak value of the dc component of load voltage to the ac voltage

Rms value of the ac component of load voltage to the dc voltage

32 / 50

In a mercury arc rectifier characteristic blue luminosity is due to_____________?

electron streams

high temperature

ionization

colour of mercury

33 / 50

The open circuit voltage of any storage cell depends wholly upon___________?

on the strength of its electrolyte

its chemical constituents

all above

its temperature

34 / 50

One D.C. motor drives another D.C. motor. The second D.C. motor when excited and driven_______________?

does not run as a generator

also runs as a motor comes to stop after sometime

runs as a generator

none

35 / 50

Two similar charges each of one coulomb placed in air one meter apart repel each other with a force______________?

9 x 107N

9 x 109N

9.2 x 104N

9 x 109N

36 / 50

Two waves of the same frequency have opposite phase when the phase angle between them is_________?

360?

90?

180?

37 / 50

AC power in a load can be controlled by using_____________?

four SCR?s in series

two SCR?s in parallel opposition

two SCR?s in series

three SCR?s in series

38 / 50

A passive network is one which contains____________?

only variable resistances

no source of e.m.f. in it

only two sources of e.m.f. in it

only some sources of e.m.f. in it

39 / 50

In AC circuits, laminated iron is invariably used in order to__________?

make assembly cheap and easier

reduce circuit permeability

reduce eddy current loss

increase heat radiation

40 / 50

The action of electromagnetic machines can be related to which of the following basic principles __________?

Interaction

All of the above

Alignment

Induction

41 / 50

The storage battery generally used in electric power station is__________?

zinc-carbon battery

lead-acid battery

none of the above

nickel-cadmium battery

42 / 50

When an SCR is turned on, the voltage across it is about _____________?

10 V

1 V

Zero

43 / 50

The self inductances of two coils are 8 mH and 18 mH. If the co-efficients of coupling is 0.5, the mutual inductance of the coils is______________?

4 mH

5 mH

6 mH

12 mH

44 / 50

The emf induced in a coil by a changing magnetic flux may have unit as______________?

ms-2A-1

ms-1A

kgm2s-1A-1

kgms2A-1

45 / 50

Load carrying capacity of belt conveyor is about___________?

50 to 100 tonnes/hr

150 to 200 tonnes/hr

20 to 40 tonnes/hr

100 to 150 tonnes/hr

46 / 50

Superhertodyne principle refers to_________________?

Obtaining lower fixed intermediate frequency

Using a push-pull circuit

Using a large number of amplifier stages

None of the above

47 / 50

The switching function of semiconductor devices can be characterized with____________?

Duty ratio, frequency and time delay

Duty ratio and frequency

Duty ratio only

Frequency only

48 / 50

For frequencies above the resonant frequency , a series LC circuit behaves as a ____________load?

None of the above

Resistive

Capacitive

Inductive

49 / 50

On which of the following variables heat convected depends ?

All of the above

Thermal resistivity, density, specific heat

Temperature difference between heated surface and coolant

Power density

50 / 50

Slip of an induction motor is negative when_____________?

rotor speed is less than the synchronous speed of the field and are in the same direction

rotor speed is more than the synchronous speed of the field and are in the same direction

magnetic field and rotor rotate in opposite direction

none of the above

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