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47 questions By Tony R. Kuphaldt
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Question 1 of 47
If a sinusoidal voltage is applied to an impedance with a phase angle of 0o, the resulting voltage and current waveforms will look like this:
Given that power is the product of voltage and current (p = i e), plot the waveform for power in this circuit.
Reveal answer
Notes:Ask your students to observe the waveform shown in the answer closely, and determine what sign the power values always are. Note how the voltage and current waveforms alternate between positive and negative, but power does not. Of what significance is this to us? What does this indicate about the nature of a load with an impedance phase angle of 0o?
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Question 2 of 47
If a sinusoidal voltage is applied to an impedance with a phase angle of 90o, the resulting voltage and current waveforms will look like this:
Given that power is the product of voltage and current (p = i e), plot the waveform for power in this circuit. Also, explain how the mnemonic phrase ËLI the ICE man” applies to these waveforms.
Reveal answer
The mnemonic phrase, ËLI the ICE man” indicates that this phase shift is due to an inductance rather than a capacitance.
Notes:Ask your students to observe the waveform shown in the answer closely, and determine what sign the power values are. Note how the power waveform alternates between positive and negative values, just as the voltage and current waveforms do. Ask your students to explain what negative power could possibly mean.
Of what significance is this to us? What does this indicate about the nature of a load with an impedance phase angle of 90o?
The phrase, ËLI the ICE man” has been used be generations of technicians to remember the phase relationships between voltage and current for inductors and capacitors, respectively. One area of trouble I’ve noted with students, though, is being able to interpret which waveform is leading and which one is lagging, from a time-domain plot such as this.
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Question 3 of 47
If a sinusoidal voltage is applied to an impedance with a phase angle of -90o, the resulting voltage and current waveforms will look like this:
Given that power is the product of voltage and current (p = i e), plot the waveform for power in this circuit. Also, explain how the mnemonic phrase ËLI the ICE man” applies to these waveforms.
Reveal answer
The mnemonic phrase, ËLI the ICE man” indicates that this phase shift is due to a capacitance rather than an inductance.
Notes:Ask your students to observe the waveform shown in the answer closely, and determine what sign the power values are. Note how the power waveform alternates between positive and negative values, just as the voltage and current waveforms do. Ask your students to explain what negative power could possibly mean.
Of what significance is this to us? What does this indicate about the nature of a load with an impedance phase angle of -90o?
The phrase, ËLI the ICE man” has been used be generations of technicians to remember the phase relationships between voltage and current for inductors and capacitors, respectively. One area of trouble I’ve noted with students, though, is being able to interpret which waveform is leading and which one is lagging, from a time-domain plot such as this.
