Electrical Energy and Capacitance4716.18Outside the spherical charge distribution, the potential is the same as for a point charge at the center of the sphere, eVkQr=(), where Thus, 91.0010CQ−=×11eefiek Qrr=−−PEqV∆=∆and from conservation of energy ( ) ( )ePE−∆KE, or 202fimvekQ−=−−−1This gives 2eefikQemrr=−v, or ( )2192Nm2 8.9910 10CC9.0.020 0 m0.030 0 mv⋅×99311.0010C1.601110kg−×××67.2510 m sv16.19From conservation of energy, ( ) ( )fiKEPEKEPE+=+, which gives 21002eifkQqrα+or ( )( )2227922eefiikeerαα==22919214227728.99 10 158 1.60 10 CC2.7410m6.6410kg2.00fr−−−⋅×16.20By definition, the work required to move a charge from one point to any other point on an equipotential surface is zero. From the definition of work, ( )cosWFsθ=⋅, the work is zero only if or 0s=cos0F=. The displacement scannot be assumed to be zero in all cases. Thus, one must require that
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This note was uploaded on 12/09/2011 for the course PHYS 2020 taught by Professor Staff during the Fall '10 term at FIU.