INTRODUCTION TO ALTERNATE CURRENT – Air – DGCA Question Bank For Politics

#1. The impedance of a circuit:

Is the AC inductive load.

Is the DC inductive load.

Is the total resistance in an AC circuit.

Is the highest resistance of a rectifier.

#2. The ratio of true power to apparent power is known as:

Ohms.

The power factor.

KVAs.

The r.m.s. value.

#3. In a constant frequency AC supply system, the frequency is determined by:

The generator drive speed and the number of poles.

Engine drive speed and the power factor.

The capacitive reactance.

The impedance.

#4. The amount of electrical power output for a given generator weight is:

Dependent on the aircrafts power requirements.

Greater for a DC generator.

Greater for an AC generator.

Determined by the size of the aircraft.

#5. The frequency of a supply is quoted in:

Cycles or Hertz.

Watts.

Megacycles.

Cycles / minute.

#6. One advantage that AC has over DC is:

That T.R.U.s are not required.

That the generators require less cooling.

That the cables require less insulation.

The ease with which the voltage can be stepped up or down with almost 100% efficiency.

#7. The voltage output of an AC generator will rise to a maximum value:

in one direction, fall to zero and rise in the same direction.

in one direction and remain there.

in one direction, fall to zero and rise to a maximum value in the opposite direction.

in one direction only.

#8. If the frequency in a circuit is less than it was designed for, then current consumption will:

decrease.

remain the same.

fluctuate.

increase.

#9. In a capacitive circuit, if the frequency increases:

current decreases.

current increases.

current flow is unaffected by frequency change.

the voltage fluctuates.

#10. The line voltage of a typical aircraft constant frequency paralleled AC system is:

115

208

200

400

#11. A 400 Hz supply has:

an output capacity of 400,000 watts.

an impedance of 400 ohms.

a frequency of 400 cycles per second.

a frequency of 400 cycles per minute.

#12. In an AC circuit which is mainly inductive:

current will lead voltage.

current and voltage will be in phase.

current will lag voltage.

the power factor will be negative.

#13. If the frequency is increased in an inductive circuit:

reactance will increase.

reactance will decrease.

impedance will remain constant.

the heating effect will increase.

#14. The r.m.s. value of alternating current is:

the mean current value for one half cycle.

1.73 times the peak value.

equal to the square root of the peak value.

.707 times the peak value.

#15. The number of separate stator windings in an AC generator determines:

the output voltage of the supply.

the output frequency of the supply.

the power factor.

the number of phases present in the supply.

#16. KVAR is a measure of:

the resistive load on the alternator.

the reactive load on the alternator.

the total load on the alternator.

the total circuit impedance.

#17. In a Star wound three phase system:

line voltage equals phase voltage and line current equals .707 times phase current

line current and voltage are 1.73 times phase current and voltage.

line current equals phase current and line voltage equals .707 times phase voltage.

line current equals phase current and line voltage equals 1.73 times phase voltage.

#18. Instruments measuring AC are calibrated in:

r.m.s. values.

average values.

peak values.

mean values.

#19. Impedance is the:

vector sum of the resistance and the reactance.

sum of the resistance and capacitive reactance.

sum of the capacitive reactance and the inductive reactance.

sum of the resistance, inductive reactance and the capacitive reactance.

#20. If an alternator is run at below normal frequency, then:

electric motors will stop.

inductive devices will overheat.

lights will become dim.

lights will become brighter.

#21. The power factor is:

KW KVAR

KVA KW

KW KVA

KVAR KW

#22. When reactance is present in a circuit:

the power factor will be unity.

the power factor will be negative.

the power factor will be greater than unity.

the power factor will be less than one.

#23. Generator output frequency is decreased by decreasing the:

generator field rotation speed.

generator field voltage.

generator field current.

generator field impedance.

#24. The r.m.s. value of AC is:

1.73 times the peak value.

the peak value times the power factor.

the peak value which would provide the same heating effect as DC

the value of DC which would provide the same heating effect.

#25. In a reactive circuit:

the voltage and current will be out of phase.

the voltage and current will be in phase opposition.

the voltage will always be led by the current.

the voltage and current will be in phase.the voltage and current will be in phase.

#26. A capacitor consists of two metal plates:

separated by a diabetic.

which have current flowing between them.

which will not allow a potential difference between them.

separated by waxed paper or mica.

#27. In a DC circuit, an inductance:

never has any effect on the voltage.

only affects the voltage upon switching on.

offers opposition to the flow while switching on and off.

will always increase the voltage.

#28. The basic unit of inductance is:

the Henry.

the Ohm.

the Farad.

the Coulomb.

#29. In an inductive circuit:

current leads the voltage.

current lags the voltage.

the voltage is in phase with the current.

only the r.m.s. values vary.

#30. In a capacitive circuit, if the frequency increases then:

current flow is unaffected.

the voltage varies.

current flow decreases.

current flow increases.

#31. The power factor is:

WATTFUL POWER REAL POWER

RATED POWER APPARENT POWER

APPARENT POWER TRUE POWER

REAL POWER APPARENT POWER

#32. Transferring electrical energy by means of a magnetic field is called:

electrostatic induction.

electromolecular induction.

electromagnetic induction.

electromolecular amplification.

#33. The output of an alternator is rated in:

KVA.

KVAR.

KW.

KW/KVAR.

Dgca Question Bank For Pilots

Results