Sulaimani University Fourth Stage College of Sciences Electromagnetic Physics Department Time: 75 minutes Q1/ Find the vector potential out of infinite solenoid with turns per unit length, radius and current . Q2/ A point charge is imbedded at the center of sphere of linear dielectric material with susceptibility and radius . Find the electric field, the polarization and the bound charge. Q3/ A certain coaxial cable consists of a copper wire, radius , surrounded by a concentric copper tube of inner radius . The space between is partially filled (from out to ) with material of dielectric constant , as shown in Fig(1). Find the stored energy in this configuration. Q4/ Find the magnetic field at point , for the steady current configuration shown in Fig(2). 2 . 1 2 Sulaimani University ‐ College of Sciences ‐ Physics Department Solution of Third Examination (30/3/2010) Electromagnetic Theory Q1/ Find the vector potential out of infinite solenoid with turns per unit length, radius and current . We cannot use the equation;
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Q2/ A point charge is imbedded at the center of sphere of linear dielectric material with susceptibility and radius . Find the electric field, the polarization and the bound charge. · 4 1
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̂ 4 1 1 · 4 1 ******************************************************* Q3/ A certain coaxial cable consists of a copper wire, radius , surrounded by a concentric copper tube of inner radius . The space between is partially filled (from out to ) with material of dielectric constant , as shown in Fig(1). Find the stored energy in this configuration. 2