PS7 - and Faraday’s law in integral form (and Lenz’s...

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Electricity and Magnetism Physics 2217 and AEP 2170 Spring 2011 Homework 7 Assigned: Monday April 11 th Due: Monday April 18 th 1. Problem 7.4 Purcell 2. Problem 7.11 Purcell 3. Problem 7.13 Purcell 4. Problem 7.14 Purcell 5. Problem 7.17 Purcell 6. Problem 7.19 Purcell 7. Problem 7.21 Purcell 8. Problem 7.22 Purcell 9. In a perfect conductor the conductivity is infinite so E =0, and any net charge resides on the surface (just as it does for an imperfect conductor, in electrostatics ). a. Show that the magnetic field is independent of time inside a perfect conductor. b. Show that the magnetic flux through a perfectly conducting loop is constant. c. A superconductor is a perfect conductor with the additional property that the B fields are excluded from the bulk interior of a superconductor, this is called the Meissner effect). Show that the current in a superconductor is confined to the surface. 10. Consider a perfect conductor and a superconductor (i.e., a perfect conductor that also displays the Meissner effect), i.e., E=0 inside either material. Using this fact
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Unformatted text preview: and Faraday’s law in integral form (and Lenz’s law), for both systems, discuss what you expect to see in the following situations (note: for this problem T Critical refers to the temperature below which both systems display perfect conductivity and above is a normal conductor). a. Cool below T C , then apply a magnetic field b. Apply magnetic field above T C , hold it, and then cool below T C in the presence of a magnetic Field. c. Cool below T C in the presence of a magnetic Field, and then remove the field. ( Challenge Problem) Superconductivity is the lost above a certain critical temperature (T C ), which varies from one material to another. Suppose you had a sphere (radius a) above its critical temperature, and you held it in a uniform magnetic field B z while cooling it below T C . Find the induced surface current density K, as a function of polar angle....
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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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