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Signal Modulation
31 questions By Tony R. Kuphaldt
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Question 25 of 31
Determine the duty cycle of this square wave signal:
Reveal answerDuty cycle ≈ 38%
Notes:This question challenges students to apply their knowledge of duty cycle to a measurement scenario.
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Question 26 of 31
Determine the duty cycle of this square wave signal:
Reveal answerDuty cycle ≈ 30%
Notes:This question challenges students to apply their knowledge of duty cycle to a measurement scenario.
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Question 27 of 31
How would a permanent-magnet DC motor respond if the switch in this circuit were repeatedly closed and opened at a very high frequency?
Would it rotate at full speed, just the same as if the switch were closed all the time? Would it rotate at all? Explain your answer.
Reveal answerThe motor would rotate at some speed less than full speed.
Follow-up question: explain how this general principle could be used to control the speed of an electric motor.
Notes:Since the circuit in this question embodies a general power control principle, it would be good to contrast it against other forms of power control. Ask your students how they think this method of control compares to that of placing a variable resistance in series with the motor. Is the “switching” method more or less efficient?
