course Phy 232 025.*********************************************
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Given Solution: `a** 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 partit ioning 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 work, 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). ** &&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&& Self-critique (if necessary): I got the first part of the answer correct, but did not derive the force function, F(x)=kQ//x^2. The integral of this would give us work, Work=kQ(1/x1-1/x2). This makes sense. Self-critique Rating:2 ********************************************* Question: `qExplain how to find the potential difference between two points given the magnitude and direction of the uniform electric field between those points. YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY Your solution: potential difference=E*dr=electric field*distance between 2 points
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Given Solution: `a** 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. ** &&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&& Self-critique (if necessary): I got it correct Self-critique Rating: 3 ********************************************* Question: `qExplain 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 YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY Your solution: Avg electric field=F/q Avg electric force= dW/ds
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Given Solution: `a** 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 ** &&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&& Self-critique (if necessary): I got it correct Self-critique Rating: 3 ********************************************* Question: `qIn your own words explain the meaning of voltage. YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY Your solution: Voltage is another name for the electric potential and is therefore the measure of charge from one unit to another.
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Given Solution: `a** Voltage is the work done per unit of charge in moving charge from one point to another. ** &&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&& Self-critique (if necessary): I got it correct, but did not include units. Self-critique Rating: 3 "