Alternating Current and Voltage Questions and Answers

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Showing 7 of 7 questions
Q1
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
Answer: Option C
Q2
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
Answer: Option B
Q3
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
Answer: Option A
Q4
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
Answer: Option C
Q5
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
Answer: Option D
Q6
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
Answer: Option D
Q7
that 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
Answer: Option B

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