Alternating Current and Voltage

Q1: What is the average voltage when a rectangular wave's base line voltage is 20 V, its peak-to-peak voltage is 50 V, and its duty cycle is 20%?

A 26 V

B 30 V

C 40 V

D 45 V

Q2:
Calculate the duty cycle of the repetitive pulse waveform in the given circuit.

A 8.33%

B 0%

C 33.33%

D 25%

Q3: Most practical alternators generate electricity from

A a coil rotating within a magnetic field

B a magnetic field rotating around fixed windings

C a permanent magnet rotating within a varying electromagnetic field

D none of the above

Q4: A single-phase induction motor

A is self-starting

B operates at a fixed speed

C is less reliable than a three-phase synchronous motor

D none of the above

Q5:
Which point is the trailing edge of the repetitive pulse waveform in the given circuit?

A Point A

B Point B

C Point C

D Point D

Q6:
What is the peak voltage across R3 in the given circuit?

A 1.2 V

B 5 V

C 7 V

D 12 V

Q7:
What type of waveform is shown in the given circuit?

A Sine wave

B Square wave

C Triangle wave

D Sawtooth wave

Q8:
What is the peak-to-peak voltage of the waveform in the given circuit?

A 2 V

B 4 V

C 6 V

D 8 V

Q9:
Calculate the positive-going slope of the waveform in the given circuit.

A 5 V/ms

B 2.5 V/ms

C 2.5 V/s

D 5 V/s

Q10: What is the instantaneous peak voltage at 250° on a 6 V peak sine wave?

A +5.64 V

B –5.64 V

C +26.13 V

D –26.13 V

Q11:
What is the dc voltage of the waveform in the given circuit?

A 2 V

B 4 V

C 6 V

D 8 V

Q12: What is the fourth harmonic of a fundamental frequency of 400 Hz?

A 100 Hz

B 4 kHz

C 4 Hz

D 1.6 kHz

Q13: A half-cycle average voltage of 12 V is equal to what rms voltage?

A 13.33 V

B 8.48 V

C 18.84 V

D 7.64 V

Q14: The effective value of a sine wave is equal to

A 0.707 of peak voltage

B 0.636 of peak voltage

C sin 45° of peak voltage

D both 0.707 of peak voltage and sin 45° of peak voltage

Q15: In both induction and synchronous ac motors

A the operating speed is very steady

B the stator magnetic field is stationary

C the stator magnetic field rotates

D the "squirrel cage" forms the rotor

Q16:
Calculate the duty cycle of the repetitive pulse waveform in the given circuit.

A 8.33%

B 0%

C 33.33%

D 25%

Q17: A rectangular wave that has a duty cycle of 50% could be called a

A "c" wave

B sawtooth wave

C square wave

D triangular wave


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