PHYS 0175 1st Edition Lecture 16Outline of Last Lecture II. CapacitorsIII. Increasing capacitanceIV. Electric Energy b/w platesV. Charging Capacitor with batteryVI. Energy Storage in CapacitorsCurrent LectureVII. DielecticsVIII.Parallel Plate and seriesIX. Electric CurrentX. Drift speedXI. Current DensityXII. Capacitance with dielecticCurrent LectureII. Dielecticsa. q/k=q-qinducedb. if Capacitance C is constant, can pull out of integralc. k=Einitial/E(by dielectic)=q/(q-qinducedd. q induced will be a fraction of charge on platee. because electric field decreases by induced dielectic materialf. Two types dielectics within two parallel platesi. If in parralell1. Equal areas for each dielectic2. New dielectic constant K’ is just the average of the twoIII. Parallel Plate and seriesa. Series charge through first determines charge through allb. Directed higher to lower potentialc. || platessame Vi. q through each depend on individual Cii. V1=V21. Q1/C1=Q2/C2IV. Electric Currenta. I=dq/dtb. Charges in motionc. Transport of charges potential energyd. Also move from higher to lower potentiale. Not a wave(because this carries mass(e-))f. Not a vectori. Flux of charge and timeg. If negative E electrons(direction for current) move opposite direction of Eh. If positive E, most in same direction as Ei. Because positive moves higher to lower, so does currenti. Electric field E gives a small drift required for a currenti. Else random motionsV. Drift speeda. vdb. caused by electric field, used in currentc. A=aread. n=#charge carrierse. q=charge on individual carrierf. how come lamp lights immediately turn on after switch?i. Already e- in wireVI. Current Densitya. J a vectori. J=nqvdii. If vd positive same directioniii. If vd negative opposite directioniv. Current I=flux of J=integral(J dot dA)VII. Capacitance with dielectica. C=k*permittivity constant*A/d=k*C(original)b. k=kappa dielectic
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