Chapter 21. Power for a resistor (18-24)

Question

3QxhZQDQ+v7PQP5i1CxHMkd1Nah3d96AnwDEVA==
{"title":"Power into a resistor","description":"Correct!","type":"correct","color":"#99CCFF","code":"[{\"shape\":\"poly\",\"coords\":\"82,133\"},{\"shape\":\"rect\",\"coords\":\"10,16,12,16\"},{\"shape\":\"poly\",\"coords\":\"144,22\"},{\"shape\":\"rect\",\"coords\":\"2,63,33,111\"}]"} {"title":"Current through the resistor","description":"Wrong","type":"incorrect","color":"#ffcc00","code":"[{\"shape\":\"rect\",\"coords\":\"87,67,107,110\"}]"} {"title":"Voltage across the resistor","description":"Incorrect","type":"incorrect","color":"#333300","code":"[{\"shape\":\"rect\",\"coords\":\"233,24,273,70\"}]"} {"title":"Resistance of the resistor","description":"Incorrect","type":"incorrect","color":"#000080","code":"[{\"shape\":\"rect\",\"coords\":\"128,63,162,108\"},{\"shape\":\"rect\",\"coords\":\"243,101,284,141\"}]"}

Question

MUUs2yh1zJAdGmNKxDUBqvbbc8u9otbaqEfLcMiEu/k=
{"title":"Power into a resistor","description":"Wrong","type":"incorrect","color":"#99CCFF","code":"[{\"shape\":\"poly\",\"coords\":\"82,133\"},{\"shape\":\"rect\",\"coords\":\"10,16,12,16\"},{\"shape\":\"poly\",\"coords\":\"144,22\"},{\"shape\":\"rect\",\"coords\":\"2,63,33,111\"}]"} {"title":"Current through the resistor","description":"Correct!","type":"correct","color":"#ffcc00","code":"[{\"shape\":\"rect\",\"coords\":\"87,67,107,110\"}]"} {"title":"Voltage across the resistor","description":"Incorrect","type":"incorrect","color":"#333300","code":"[{\"shape\":\"rect\",\"coords\":\"233,24,273,70\"}]"} {"title":"Resistance of the resistor","description":"Incorrect","type":"incorrect","color":"#000080","code":"[{\"shape\":\"rect\",\"coords\":\"128,63,162,108\"},{\"shape\":\"rect\",\"coords\":\"243,101,284,141\"}]"}

Question

mMeCJb9LYec2D9sQzVDfFznir2p5Al8/VvdKHLmgcLA=
{"title":"Power into a resistor","description":"Wrong","type":"incorrect","color":"#99CCFF","code":"[{\"shape\":\"poly\",\"coords\":\"82,133\"},{\"shape\":\"rect\",\"coords\":\"10,16,12,16\"},{\"shape\":\"poly\",\"coords\":\"144,22\"},{\"shape\":\"rect\",\"coords\":\"2,63,33,111\"}]"} {"title":"Current through the resistor","description":"Wrong","type":"incorrect","color":"#ffcc00","code":"[{\"shape\":\"rect\",\"coords\":\"87,67,107,110\"}]"} {"title":"Voltage across the resistor","description":"Correct!","type":"correct","color":"#333300","code":"[{\"shape\":\"rect\",\"coords\":\"233,24,273,70\"}]"} {"title":"Resistance of the resistor","description":"Incorrect","type":"incorrect","color":"#000080","code":"[{\"shape\":\"rect\",\"coords\":\"128,63,162,108\"},{\"shape\":\"rect\",\"coords\":\"243,101,284,141\"}]"}

Question

Be2tWOBxdYEcD2Q3lcFQtZd/9iWt2NqbSFGqNvkPlwY=
{"title":"Power into a resistor","description":"Wrong","type":"incorrect","color":"#99CCFF","code":"[{\"shape\":\"poly\",\"coords\":\"82,133\"},{\"shape\":\"rect\",\"coords\":\"10,16,12,16\"},{\"shape\":\"poly\",\"coords\":\"144,22\"},{\"shape\":\"rect\",\"coords\":\"2,63,33,111\"}]"} {"title":"Current through the resistor","description":"Wrong","type":"incorrect","color":"#ffcc00","code":"[{\"shape\":\"rect\",\"coords\":\"87,67,107,110\"}]"} {"title":"Voltage across the resistor","description":"Incorrect","type":"incorrect","color":"#333300","code":"[{\"shape\":\"rect\",\"coords\":\"233,24,273,70\"}]"} {"title":"Resistance of the resistor","description":"Correct!","type":"correct","color":"#000080","code":"[{\"shape\":\"rect\",\"coords\":\"128,63,162,108\"},{\"shape\":\"rect\",\"coords\":\"243,101,284,141\"}]"}

Review

Figure 21-2 graphs the voltage \(V(t)\) as a function of time. The angular frequency \(\omega\) of the voltage (in rad/s) is related to the frequency \(f\) of the voltage (in Hz) by the same relationship we used in Section 12-3 for simple harmonic motion:

\(\omega = 2\pi{f}\)

The period \(T\) of the oscillation is equal to \(1/f\). For example, in the United States and Canada ac voltage is applied at a frequency \(f = 60\ \mathrm{Hz}\), so the period of oscillation is \(T = 1/f = 1/ (60\ \mathrm{Hz})= 0.017 \mathrm{s}\) and the angular frequency is \(\omega = 2\pi{f} = (2\pi\mathrm{rad})\ (60\ \mathrm{Hz}) = 3.8 \times 10^2\ \mathrm{rad}/s\).

If we attach a source of ac voltage described by Equation 21-1 to a resistor of resistance \(R\), we can still use Equation 18-24 to calculate the power that flows into the resistor:

.