course Phy 122 I didn't do that well on this one. I have a hard time visualizing without data. I did take notes on this and think that it may have helped me figure it out. ¢¹¸~Àîšôв€ÎºÐŽÙÏ˾ÛÑØæªÉ¿™assignment #004
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13:08:58 Query introductory set #1, 10-17 Explain how to find the potential difference in volts between two given points on the x axis, due to a given charge at the origin.
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RESPONSE --> The magnitude of the field is given as 98v/m The charge moved .15m, so the difference in potential from the origin to .15 m would be .15m*98v/m=14.7v confidence assessment: 2
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13:13:38 ** Potential difference is the work per Coulomb of charge moved between the two points. To find this work you can multiply the average force on a Coulomb of charge by the displacement from the first point to the second. You can find an approximate average force by finding the force on a 1 Coulomb test charge at the two points and averaging the two forces. Multiplying this ave force by the displacement gives an approximate potential difference. Since the force is not a linear function of distance from the given charge, if the ratio of the two distances from the test charge is not small the approximation won't be particularly good. The approximation can be improved to any desired level of accuracy by partitioning the displacement between charges into smaller intervals of displacement and calculating the work done over each. The total work required is found by adding up the contributions from all the subintervals. University Physics students should understand how this process yields the exact w ""ork, which is the integral of the force function F(x) = k Q / x^2 between the two x values, yielding total work W = k * Q * 1 Coulomb ( 1 / x1 - 1 / x2) and potential difference V = k * Q ( 1 / x1 - 1 / x2). **
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RESPONSE --> I think that is what I did self critique assessment: 1
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13:27:26 Explain how to find the potential difference between two points given the magnitude and direction of the uniform electric field between those points.
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RESPONSE --> If you know the magnitude of the field and the direction of the field, you can determine if the work done by the charge is negative or positive, but without having the points I'm unsure of how to obtain an aswer. confidence assessment: 0
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13:30:31 ** The work per Coulomb done between the two points is equal to the product of the electric field E and the displacement `dr. Thus for constant field E we have V = E * `dr. **
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RESPONSE --> I can see that now. I have a hard time visualizing this without actual values. self critique assessment: 2
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13:41:26 Explain how to find the average electric field between two points given a specific charge and the work done on the charge by the electric field as the charge moves between the points.
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RESPONSE --> I was able to do the problem sets, but for some reason I'm not following without actual values. confidence assessment: 0
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13:44:44 ** You get ave force from work and distance: F_ave = `dW / `ds. You get ave electric field from work and charge: E_ave = F / q. An alternative: Find potential difference `dV = `dW / q. Ave electric field is Eave = `dV / `ds **
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RESPONSE --> When I see it written I can follow. self critique assessment: 1
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13:47:02 In your own words explain the meaning of voltage.
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RESPONSE --> Voltage is a difference of potential. It is the differnce from one charge to another. confidence assessment: 2
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13:49:08 ** Voltage is the work done per unit of charge in moving charge from one point to another. **
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RESPONSE --> OK I see that definition. v=j/c self critique assessment: 2
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