course Phy 202
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21:11:19 `questionNumber 40000 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 --> Well, the work is obviously force*displacement. I guess since the origin is known, the only way to fin the volts and differnece of 2 points is to somehow calculate potential difference at 2 points and average them but I don't know. confidence assessment: 1
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21:12:22 `questionNumber 40000 ** 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 see now that I was on the right track and lesat: I should find the force of a 2 C test charage and then find the potential difference by multiplying the average force by displacement. self critique assessment: 2
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21:12:57 `questionNumber 40000 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 --> electric field*displacement confidence assessment: 2
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21:13:03 `questionNumber 40000 ** 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 undesrtand. self critique assessment: 3
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21:15:20 `questionNumber 40000 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 think for this we just use the formula frmo last semester: Work=F*'ds, so F='dW/'ds confidence assessment: 2
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21:15:27 `questionNumber 40000 ** 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 --> I understand. self critique assessment: 2
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21:15:59 `questionNumber 40000 In your own words explain the meaning of voltage.
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RESPONSE --> I guess voltage is how much work is doen in moving a charge from one point to another. confidence assessment:
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21:16:16 `questionNumber 40000 ** Voltage is the work done per unit of charge in moving charge from one point to another. **
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RESPONSE --> I didn't get the ""per unit of charge"" part, but I got the gist. self critique assessment: 2
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