course phy 122 Did not know how to find the average electrical field. assignment #004004.
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18:11:21 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 potential energy difference divided by the charge, or the potential energy difference per unit charge. confidence assessment: 1
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18:11:57 ** 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 --> sounds good. I would be unable to diecribe it like that. self critique assessment: 1
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18:19:08 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 --> The potential difference between two points in an electric field is defined as the work required to move a unit positive test charge from the point of lower potential to that of higher potential. confidence assessment: 1
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18:19:25 ** 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 --> ok self critique assessment: 0
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19:00:27 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 --> Not sure confidence assessment: 0
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19:01:22 ** 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 looked this up in the text, and on the internet. It is obvious my grasp on the subject matter is so superficial I could not reason this out. self critique assessment: 1
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19:02:37 In your own words explain the meaning of voltage.
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RESPONSE --> Difference of electrical potential between two points of an electrical circuit, expressed in volts. confidence assessment: 1
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19:02:42 ** Voltage is the work done per unit of charge in moving charge from one point to another. **
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RESPONSE --> self critique assessment: 3
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