DGCA AC Electrics 1. Introduction to AC

 

Results

Q1. The impedance of a circuit:

Correct answer is – is the total resistance in an AC circuit

Q2. The ratio of true power to apparent power is known as:

Correct answer is – the power factor

Q3. In a constant frequency AC supply system, the frequency is determined by:

Correct answer is – the generator drive speed and the number of poles

Q4. The amount of electrical power output for a given generator weight is:

Correct answer is – greater for an AC generator

Q5. The frequency of a supply is quoted in:

Correct answer is – cycles or hertz

Q6. One advantage that AC has over DC is:

Correct answer is – the ease with which the voltage can be stepped up or down with almost 100% efficiency

Q7. The voltage output of an AC generator will rise to a maximum value:

Correct answer is – in one direction, fall to zero and rise to a maximum value in the opposite direction

Q8. If the frequency in an inductive circuit is less than it was designed for, then current consumption will:

Correct answer is – increase

Q9. In a capacitive circuit, if the frequency increases:

Correct answer is – current increases

Q10. The line voltage of a typical aircraft constant frequency paralleled AC system is:

Correct answer is – 200

Q11. A 400 Hz supply has:

Correct answer is – a frequency of 400 cycles per second

Q12. In an AC circuit which is mainly inductive:

Correct answer is – current will lag voltage

Q13. If the frequency is increased in an inductive circuit:

Correct answer is – reactance will increase

Q14. The RMS value of alternating current is:

Correct answer is – .707 times the peak value

Q15. The number of separate stator windings in an AC generator determines:

Correct answer is – the number of phases present in the supply

Q16. kVAR is a measure of:

Correct answer is – the reactive load on the alternator

Q17. The output of an alternator is rated in:

Correct answer is – kVA

Q18. Instruments measuring AC are calibrated in:

Correct answer is – RMS values

Q19. Impedance is the:

Correct answer is – vector sum of the resistance and the reactance

Q20. If an alternator is run at below normal frequency, then:

Correct answer is – inductive devices will overheat

Q21. The power factor is:

Correct answer is – kW / kVA

Q22. When reactance is present in a circuit:

Correct answer is – the power factor will be less than one

Q23. Generator output frequency is decreased by decreasing the:

Correct answer is – generator field rotation speed

Q24. The RMS value of AC is:

Correct answer is – the value of DC which would provide the same heating effect

Q25. In a reactive circuit:

Correct answer is – the voltage and current will be out of phase

Q26. A capacitor consists of two metal plates:

Correct answer is – separated by waxed paper or mica

Q27. In a DC circuit, an inductance:

Correct answer is – offers opposition to the flow while switching on and off

Q28. The basic unit of inductance is:

Correct answer is – the henry

Q29. In an inductive circuit:

Correct answer is – current lags the voltage

Q30. In a capacitive circuit, if the frequency increases then:

Correct answer is – current flow increases

Q31. The power factor is:

Correct answer is – REAL POWER / APPARENT POWER

Q32. Transferring electrical energy by means of a magnetic field is called:

Correct answer is – electromagnetic induction

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