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What is Physics Good For?

Warming up on... AC Circuits and Resonance

This assignment is due before 9 AM, Monday, October 22^nd, 2007.

Please type your last name and first initial (e.g., Rader, A):

Please type a nickname: (in case your answer gets used in class).

The following questions refer to the material you were to read in preparation to the lesson. Please write a three or four sentence response to each of the questions.

You may change your mind as often as you wish. When you are satisfied with your responses, click the SUBMIT HOMEWORK button at the bottom of this page.

WarmUp questions are worth 4 points.

1.

In your own words, please explain what an impedance is. Also, please explain the difference between the L-R-C circuit discussed in section 31-3 and the L-R-C circuit discussed in section 30-6.

2.

You make a parallel plate capacitor by using two sheets of aluminum foil for plates, and a sheet of notebook paper to hold them apart. Estimate the reactance of your capacitor at 60 Hz.

3.

In a series R-L-C circuit, which of the following statements is true at resonance?

The source power and the phase angle are both maximized.

The source power and the phase angle are both zero.

The source power is zero but the phase angle is large.

The source power is large but the phase angle is zero.

None of the above.

4.

Consider two sinusoidal signals, V₁(t) = V_maxcos(t), and V₂(t) = V_maxcos(t+/3). Which of these signals leads the other? In the figure, is the one on the left leading or lagging? What does it mean for one signal to lead (or lag) another.

Below is a space for your thoughts, including general comments about today's assignment. What was hard or confusing (or cool)? What would you like to spend extra time on in class? Do you see how this subject fits in with the others we have discussed?

You may change your mind as often as you wish. When you are satisfied with your responses click the SUBMIT button.

This site is made possible by funding from the National Science Foundation (DUE-9981111).

This assignment is due before 9 AM, Monday, October 22nd, 2007.

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This assignment is due before 9 AM, Monday, October 22^nd, 2007.