Electrical Engineering Quiz 65

1 / 50

Superhertodyne principle refers to_________________?

Using a large number of amplifier stages

Obtaining lower fixed intermediate frequency

None of the above

Using a push-pull circuit

2 / 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

3 / 50

Insulating materials have the function of___________?

preventing a short circuit between conducting wires

storing very high currents

conducting very large currents

preventing an open circuit between the voltage source and the load

4 / 50

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

All

none of the above

wheel base of axles is more

degree of curvature is more

5 / 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

6 / 50

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

Series motor

Cumulatively compounded motor

Differentially compounded motor

Shunt motor

7 / 50

Which of the following is reversible in action ?

Motor converter

Rotary converter

Any of the above

Motor generator set

8 / 50

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

None of the above

Only the difference frequency can be modulated

The difference frequency is closer to oscillator frequency

Lower frequencies are easier to amplify

9 / 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 .

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

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

10 / 50

The active materials of a nickel-iron battery are___________?

powdered iron and its oxide

21% solution of KOH

all of the above

nickel hydroxide

11 / 50

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

Inductance

All of the above

Capacitance

Resistance

12 / 50

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

nil

none of the above

minimum

maximum

13 / 50

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

180?

360?

90?

14 / 50

A steam power station requires space______________?

more than diesel power station

None

equal to diesel power station

less than diesel power station

15 / 50

Electric displacement is a__________quantity

both of the above

scalar

none of the above

vector

16 / 50

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

Supercharged engine

All of the above engines will equal power

Diesel engine

Petrol engine

17 / 50

Load carrying capacity of belt conveyor is about___________?

50 to 100 tonnes/hr

150 to 200 tonnes/hr

100 to 150 tonnes/hr

20 to 40 tonnes/hr

18 / 50

Which of the following can be measured by LVDT ?

Displacement

Any of the above

Acceleration

Velocity

19 / 50

The storage battery generally used in electric power station is__________?

nickel-cadmium battery

none of the above

zinc-carbon battery

lead-acid battery

20 / 50

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

Inductive

Resistive

Capacitive

None of the above

21 / 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

remains same as the original value

increases to two times the original value

tends to becomes zero

22 / 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

23 / 50

Ripple factor is the ratio of______________________?

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

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

24 / 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?

12 V

6 V

5.7 V

0.57 V

25 / 50

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

100 uF

200 uF

400 uF

300 uF

26 / 50

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

Interaction

Induction

All of the above

Alignment

27 / 50

With feed back ____________ reduces?

system stability

system stability and gain

system gain

none of the above

28 / 50

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

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

can be used for 50?C ambient temperature also

of lower H.P. should be selected

29 / 50

Excessive charging a battery tends to____________?

increase the internal resistance of the battery

produce gassing

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

bring about all above changes

30 / 50

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

results in sparking trouble

increases armature speed

reduces interpoles flux density

reduces generator e.m.f.

31 / 50

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

electron streams

high temperature

ionization

colour of mercury

32 / 50

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

oscillatory

overdamped

underdamped

critically damped

33 / 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

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

runs as a generator

none

also runs as a motor comes to stop after sometime

35 / 50

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

average value

peak value

mean value

r.m.s. value

36 / 50

Slip of an induction motor is negative when_____________?

none of the above

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

37 / 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

38 / 50

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

Zero

1 V

10 V

1 V

39 / 50

The fuel used in nuclear reactor is_____________?

radium

cadmium

all of the above

uranium

40 / 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______________?

6 mH

12 mH

4 mH

5 mH

41 / 50

AC power in a load can be controlled by using_____________?

three SCR?s in series

four SCR?s in series

two SCR?s in series

two SCR?s in parallel opposition

42 / 50

A transistor is a___________operated device?

voltage

current

none of the above

both voltage and current

43 / 50

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

kgms2A-1

kgm2s-1A-1

ms-2A-1

ms-1A

44 / 50

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

true power

instantaneous power

volt-amperes

reactive power

45 / 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 600 ?

is less than 6 k?

46 / 50

Induction type single phase energy meters measure electric energy in_______________?

VAR

kWh

47 / 50

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

on the strength of its electrolyte

all above

its temperature

its chemical constituents

48 / 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

49 / 50

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

3 V

Zero

0.3 V

5 V

50 / 50

As the breakdown voltage reached, the DIAC exhibits?

All of these

Goes into avalanche condition

Voltage drop snaps back

Negative resistance characteristics

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