# PS4 - about it 9 Problem 3.32 Purcell These are good...

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Electricity and Magnetism Physics 2217 and AEP 2170 Spring 2011 Homework 4 Assigned: Wed February 16 th Due: Friday February 25 th 1. Problem 3.01 Purcell 2. Problem 3.05 Purcell 3. Problem 3.07 Purcell 4. Problem 3.09 Purcell 5. Problem 3.11 Purcell 6. Problem 3.14 Purcell 7. Problem 3.18 Purcell. Great problem! Additionally (or in the process of answering the question asked by Purcell), calculate the stored energy for fixed y, i.e., fixed location of sheet-A. Does the energy increase or decrease as you lower the position, i.e., increase y, of sheet A? What if, rather than the charge on A being fixed, that instead the potential on A were fixed (by hooking it up to a constant voltage source), what happens to the charge on A as you lower A, i.e., as you increase y? What happens to the energy? What is the force on A? 8. Problem 3.23a Purcell (Part b explores similar physics as 3.18, go ahead and think
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Unformatted text preview: about it!) 9. Problem 3.32 Purcell These are good problems. You should solve them!! But don’t need to hand in IF you run out of time this week (answers given in Purcell) 10. Problem 3.10 Purcell 11. Problem 3.17 Purcell Challenge Problem (you do not have to hand this in). The electric potential of some configuration is given by the expression [ V(r) = A e-λ r /r ]where A and λ are constants. Find the electric field, the charge density ρ , and the total charge Q. [part of answer: ρ (r) = A/(4 π k) (4 π δ 3 (r) - λ 2 e-λ r /r) where δ 3 (r) = δ (x) δ (y) δ (z) is the Dirac delta function in 3-d, see Griffiths chapter 1.] Note this form of a potential, the Yukawa potential, shows up in Particle physics, Nuclear physics, and Condensed Matter physics (where it is called the screened Coulomb potential, why “screened” and what is doing the screening?)!...
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## This note was uploaded on 06/10/2011 for the course PHYS 2217 taught by Professor Leclair, a during the Spring '06 term at Cornell.

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