Four charges: +q,−q,+2q, and −2q are assembled around a square with side length a as shown in the figure.

Sunday, 26 August 2018

12:53 AM

Machine generated alternative text: Question: a 02 1 O 30 4 O Figure 1. Four charges: +q, —q, +2q, and —2q are assembled around a square witn side length a. Four charges: +q, —q, +2q, and —2q are assembled around a square witn side length a as shown in the figure. In this case q place at the origin (0, 0). The potential an infinite distance from a point charge is 0 (V = 0). part 1) What is the potential at (0, 17.92) cm when only the = 4-8.99gC charge is in place? part 2) 8.99gC and a 17.92 cm. Initially the only charge +q is in What is the change in potential energy of the system when just the A-q charge is in place and the —2q charge is moved trom an infinite distance away to (0, 17.92). part 3) What is the change in potential energy of the system as the entire ensemble of charges is constructed? The charges are moved from an infinite distance away to their position one by one. Check

 

Machine generated alternative text: Feedback tor Part 1) The potential a distance a from a point charge witn charge is given by: In this case, q = -Fq and d = a so: Remember to convert q from "C to C and a trom cm to m. Marks for this submissiom 0.00/0.33. This submission attracted a penalty of 0.11 47rE0 d • 47rE0 a

 

Machine generated alternative text: Feedback tor Part 3) Figure 1 _ Four charges: —q, +2q, and —2q are assembled around a square witn side length a. Assume that the charges are placed in the order shown on the figure (all orders give the same final answer). No work needs to be done to place the first charge as there is no electric field so AUI = o. The change in potential energy to place the second charge was calculated in part 2 so: AU2 27rE0 a The third charge is placed into the potential caused by the first two charges: AU3 The tourtn charge is placed into the potential caused by the first three charges: AU4 47TE0 4mE0 47rE0 Via 47TE0 a v'5a 47rE0 v/5a a 47rE0

 

Machine generated alternative text: The total change in potential energy can be calculated by summing these: 1 47rE0 AU = AUI + AU2 + AU3 + AU4 —2q2 4q2 47rE0 2q2 2q2 q —9q (_90+4) . Marks for this submissiom 0.00/0.33. This submission attracted a penalty of 0.11 A correct answer is 451000, which can be typed in as follows: 451eaa A correct answer -8.11 A correct answer —8.11, which can be typed in as follows: —25, which can be typed in as follows:

 

 

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