Figure 1. There are two charged coaxial cylinders of length l. The inner cylinder has radius r with charge +Q and the outer cylinder has radius r+d with charge −Q.

Sunday, 26 August 2018

1:06 AM

Machine generated alternative text: Question: -Q Figure 1 _ There are üo charged coaxial cylinders ot length l. The inner cylinder has radius r with charge +Q and the outer cylinder nas radius T + d witn charge —Q Two thin, coaxial, hollow cylinders Witn length I are charged with equal but opposite charges +Q and —Q. T ne inner cylinder has a radius r, while the outer cylinder nas a radius T + d, as shown in the tigure_ I r + d (so you can neglect end effects: the sketch is not to scale.) In this question use eo in any expressions, not Coulomb's constant part 1) Write an expression tor the magnitude ottne electric tield at a point a radius R trom the axis ot the üo cylinders, where r < R < T + d, that is the point is between the two cylinders. part 2) Write an expression tor the potential beüeen the two cylinders. part 3) use this expression to write an expression tor the capacitance of this system. Check

 

Machine generated alternative text: Feedback tor Part 1) Figure 1 _ A cylindrical Gaussian surface (dashed line) of length I is set up between the two cylinders witn radius r < R < r + d. use a cylinder with length y, y < I and radius R as the Gaussian surface for this problem. In this case: This electric field lines do not pass through the cylinder surfaces so A The enclosed charge is all on the inner cylinder so qenc = This tells us that: 2nRy. E. 2nRy Marks for this submissiom 0.00/0.33. This submission attracted a penalty of 0.11 Feedback tor Part 2) To calculate the potential we can use AV—fE. ds. (In(r + d) — In(r)) Marks for this submissiom 0.00/0.33. This submission attracted a penalty of 0.11

 

Feedback tor Part 3) The capacitance is given by: In this case AV Q this is negative so IAVI = 2KIeo r4d IAVI • Q 2 TIEO In( r+rd ) • Marks for this submissiom 0.00/0.33. This submission attracted a penalty of 0.11 A correct answer is , which can be typed in as follows Q In(rld) A correct answer , which can be typed in as follows: A correct answer is , which can be typed in as follows:

 

 

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