Electrical Engineering Quiz 65

1 / 50

Which of the following statements is incorrect ?

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

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

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

2 / 50

The active materials of a nickel-iron battery are___________?

all of the above

powdered iron and its oxide

21% solution of KOH

nickel hydroxide

3 / 50

With feed back ____________ reduces?

system stability and gain

none of the above

system stability

system gain

4 / 50

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

increases armature speed

reduces interpoles flux density

results in sparking trouble

reduces generator e.m.f.

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_____________?

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

of lower H.P. should be selected

6 / 50

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

100 uF

200 uF

300 uF

400 uF

7 / 50

A transistor is a___________operated device?

current

none of the above

both voltage and current

voltage

8 / 50

The storage battery generally used in electric power station is__________?

lead-acid battery

zinc-carbon battery

nickel-cadmium battery

none of the above

9 / 50

Slip of an induction motor is negative when_____________?

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

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

10 / 50

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

Induction

Interaction

All of the above

Alignment

11 / 50

The fuel used in nuclear reactor is_____________?

cadmium

uranium

radium

all of the above

12 / 50

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

reactive power

true power

instantaneous power

volt-amperes

13 / 50

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

high temperature

colour of mercury

ionization

electron streams

14 / 50

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

5 V

3 V

Zero

0.3 V

15 / 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

remains same as the original value

increases to two times the original value

16 / 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

none

runs as a generator

also runs as a motor comes to stop after sometime

17 / 50

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

Zero

10 V

1 V

18 / 50

The switching function of semiconductor devices can be characterized with____________?

Duty ratio, frequency and time delay

Duty ratio and frequency

Frequency only

Duty ratio only

19 / 50

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

maximum

nil

none of the above

minimum

20 / 50

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

Inductance

Capacitance

Resistance

All of the above

21 / 50

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

Differentially compounded motor

Cumulatively compounded motor

Shunt motor

Series motor

22 / 50

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

9 x 109N

9 x 107N

9.2 x 104N

23 / 50

Which of the following can be measured by LVDT ?

Displacement

Velocity

Any of the above

Acceleration

24 / 50

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

is less than 600 ?

is less than 1.2 k?

is greater than 1.2 k?

is less than 6 k?

25 / 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

26 / 50

Electric displacement is a__________quantity

both of the above

scalar

vector

none of the above

27 / 50

As the breakdown voltage reached, the DIAC exhibits?

All of these

Goes into avalanche condition

Negative resistance characteristics

Voltage drop snaps back

28 / 50

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

ms-2A-1

ms-1A

kgms2A-1

kgm2s-1A-1

29 / 50

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

critically damped

oscillatory

underdamped

overdamped

30 / 50

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

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

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

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

All of the above

31 / 50

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

Inductive

Resistive

Capacitive

None of the above

32 / 50

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

average value

peak value

r.m.s. value

mean value

33 / 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

wheel base of axles is more

none of the above

34 / 50

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

Supercharged engine

Diesel engine

All of the above engines will equal power

Petrol engine

35 / 50

Superhertodyne principle refers to_________________?

None of the above

Obtaining lower fixed intermediate frequency

Using a large number of amplifier stages

Using a push-pull circuit

36 / 50

A passive network is one which contains____________?

no source of e.m.f. in it

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

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

only variable resistances

37 / 50

Load carrying capacity of belt conveyor is about___________?

100 to 150 tonnes/hr

50 to 100 tonnes/hr

150 to 200 tonnes/hr

20 to 40 tonnes/hr

38 / 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

39 / 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

6 V

5.7 V

12 V

40 / 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

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

41 / 50

Induction type single phase energy meters measure electric energy in_______________?

kWh

VAR

42 / 50

Which of the following is reversible in action ?

Any of the above

Rotary converter

Motor generator set

Motor converter

43 / 50

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

all above

its temperature

its chemical constituents

on the strength of its electrolyte

44 / 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______________?

12 mH

4 mH

6 mH

5 mH

45 / 50

AC power in a load can be controlled by using_____________?

four SCR?s in series

three SCR?s in series

two SCR?s in series

two SCR?s in parallel opposition

46 / 50

Insulating materials have the function of___________?

conducting very large currents

preventing an open circuit between the voltage source and the load

preventing a short circuit between conducting wires

storing very high currents

47 / 50

Excessive charging a battery tends to____________?

produce gassing

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

increase the internal resistance of the battery

bring about all above changes

48 / 50

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

180?

90?

360?

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

A steam power station requires space______________?

more than diesel power station

None

less than diesel power station

equal to diesel power station

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