43. (a) The electric feld in the region between the plates is given byE=V/d,whereVis the potentialdiFerence between the plates anddis the plate separation. The capacitance is given byC=κε0A/d,whereAis the plate area andκis the dielectric constant, sod=κε0A/CandE=VCκε0A=(50 V)(100×10−12±)5.4(8.85×10−12±/m)(100×10−4m2)=1.0×104V/m.(b) The ²ree charge on the plates isqf=CV= (100×10−12±)(50 V) = 5.0×10−9C.(c) The electric feld is produced by both the ²ree and induced charge. Since the feld o² a large uni²ormlayer o² charge isq/2ε0A, the feld between the plates isE=qf2ε0A+qf2ε0A−qi2ε0A−qi2ε0A,where the frst term is due to the positive ²ree charge on one plate, the second is due to the negative
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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.