66.(a) We denote the surface charge density of the disk asσ1for 0<r<R/2, and asσ2forR/2<r<R.Thus the total charge on the disk is given byq=Zdiskdq=ZR/202πσ1rdr+ZRR/222=π4R2(σ1+3σ2)=π4(2.20×10−2m)2[1.50×10−6C/m2+3(8.00×10−7C/m2)]=1.48×10−9C.(b) We use Eq. 25-36:V(z)=ZdiskdV=k· ZR/20σ1(2πR0)dR0√z2+R02+ZRR/2σ2(20)dR0√z2+R02¸=σ
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This note was uploaded on 11/12/2011 for the course PHYS 2001 taught by Professor Sprunger during the Fall '08 term at LSU.