Electrical Engineering Quiz 65

1 / 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

2 / 50

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

reactive power

volt-amperes

true power

instantaneous power

3 / 50

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

reduces interpoles flux density

results in sparking trouble

reduces generator e.m.f.

increases armature speed

4 / 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?

5.7 V

12 V

0.57 V

6 V

5 / 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 lower H.P. should be selected

can be used for 50?C ambient temperature also

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

of higher H.P. should be selected

6 / 50

Load carrying capacity of belt conveyor is about___________?

50 to 100 tonnes/hr

100 to 150 tonnes/hr

150 to 200 tonnes/hr

20 to 40 tonnes/hr

7 / 50

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

None of the above

Capacitive

Inductive

Resistive

8 / 50

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

runs as a generator

does not run as a generator

none

also runs as a motor comes to stop after sometime

9 / 50

The storage battery generally used in electric power station is__________?

none of the above

lead-acid battery

zinc-carbon battery

nickel-cadmium battery

10 / 50

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

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

All of the above

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

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

11 / 50

The fuel used in nuclear reactor is_____________?

radium

cadmium

uranium

all of the above

12 / 50

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

its chemical constituents

its temperature

all above

on the strength of its electrolyte

13 / 50

A steam power station requires space______________?

equal to diesel power station

less than diesel power station

more than diesel power station

None

14 / 50

A passive network is one which contains____________?

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

no source of e.m.f. in it

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

only variable resistances

15 / 50

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

Capacitance

Inductance

Resistance

All of the above

16 / 50

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

Diesel engine

Petrol engine

Supercharged engine

All of the above engines will equal power

17 / 50

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

300 uF

200 uF

400 uF

100 uF

18 / 50

On which of the following variables heat convected depends ?

All of the above

Power density

Temperature difference between heated surface and coolant

Thermal resistivity, density, specific heat

19 / 50

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

1 V

Zero

1 V

10 V

20 / 50

The switching function of semiconductor devices can be characterized with____________?

Duty ratio and frequency

Frequency only

Duty ratio only

Duty ratio, frequency and time delay

21 / 50

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

ms-2A-1

kgm2s-1A-1

ms-1A

kgms2A-1

22 / 50

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

Series motor

Differentially compounded motor

Shunt motor

Cumulatively compounded motor

23 / 50

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

overdamped

underdamped

critically damped

oscillatory

24 / 50

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

maximum

nil

minimum

none of the above

25 / 50

Excessive charging a battery tends to____________?

produce gassing

bring about all above changes

increase the internal resistance of the battery

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

26 / 50

AC power in a load can be controlled by using_____________?

four SCR?s in series

two SCR?s in series

three SCR?s in series

two SCR?s in parallel opposition

27 / 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 600 ?

is less than 6 k?

is less than 1.2 k?

28 / 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

tends to becomes zero

increases to two times the original value

remains same as the original value

29 / 50

Electric displacement is a__________quantity

scalar

none of the above

vector

both of the above

30 / 50

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

Only the difference frequency can be modulated

None of the above

Lower frequencies are easier to amplify

The difference frequency is closer to oscillator frequency

31 / 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

12 mH

5 mH

6 mH

32 / 50

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

reduce eddy current loss

reduce circuit permeability

make assembly cheap and easier

increase heat radiation

33 / 50

The active materials of a nickel-iron battery are___________?

21% solution of KOH

nickel hydroxide

powdered iron and its oxide

all of the above

34 / 50

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

Induction

Interaction

All of the above

Alignment

35 / 50

Ripple factor is the ratio of______________________?

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

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

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

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

36 / 50

Which of the following is reversible in action ?

Any of the above

Motor converter

Rotary converter

Motor generator set

37 / 50

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

Zero

5 V

3 V

0.3 V

38 / 50

Superhertodyne principle refers to_________________?

Obtaining lower fixed intermediate frequency

None of the above

Using a large number of amplifier stages

Using a push-pull circuit

39 / 50

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

r.m.s. value

peak value

mean value

average value

40 / 50

With feed back ____________ reduces?

system stability

system gain

system stability and gain

none of the above

41 / 50

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

high temperature

colour of mercury

ionization

electron streams

42 / 50

Induction type single phase energy meters measure electric energy in_______________?

kWh

VAR

43 / 50

A transistor is a___________operated device?

voltage

current

none of the above

both voltage and current

44 / 50

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

90?

360?

180?

45 / 50

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

All

degree of curvature is more

none of the above

wheel base of axles is more

46 / 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

magnetic field and rotor rotate in opposite direction

none of the above

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

47 / 50

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

9 x 109N

9.2 x 104N

9 x 107N

9 x 109N

48 / 50

Which of the following can be measured by LVDT ?

Velocity

Displacement

Acceleration

Any of the above

49 / 50

As the breakdown voltage reached, the DIAC exhibits?

Voltage drop snaps back

Negative resistance characteristics

All of these

Goes into avalanche condition

50 / 50

Which of the following statements is incorrect ?

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

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

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