4/20/11 1 Physics 1224/20/11 2 Physics 1224/20/11 5 Physics 1224/20/11 6 Physics 1224/20/11 7 Physics 1224/20/11 8 Physics 122 nuclei Shared electron cloud4/20/11 9 Physics 1224/20/11 10 Physics 1224/20/11 11 Physics 122 APF=1 2 3 44/20/11 12 Physics 122 Fdrag= 8πμLv4/20/11 13 Physics 122 Flow in Flow out Pressure force upstream Pressure force downstream Drag force4/20/11 14 Physics 122 Pupstream A L Pdownstream A R F dragΔPA= 8πμLvΔPA= 8πμLQA⎛⎝⎜⎞⎠⎟ΔP =8πμLA2⎛⎝⎜⎞⎠⎟Q =8μLπR4⎛⎝⎜⎞⎠⎟QΔP = QZPressure drop = (Flow)(Resistance)Flow: Q = vol/sec = Av4/20/11 15 Physics 122 Constant flow of charge through a resistor. “Resistance” (energy produced – e.g. in lightbulb) Drag force on the electrons? Guess -bv Must be some kind of “pressure drop” corresponding to the electric force.4/20/11 16 Physics 122 No resistance constant v even without gravity No resistance constant v even without gravity Resistance constant v even with gravity (mg=bv)4/20/11 17 Physics 1224/20/11 18 Physics 122 Pump constant v Does work against gravity Rises by Δh No resistance constant v No change in h Resistance constant v gravity pushing (mg sin θ = bv) Drops by Δh.4/20/11 19 Physics 122 No resistance constant v even without electric force No resistance constant v even without electric force Resistance constant v even with electric force (Fe = bv) Buildup of negative charge Shortage of negative charge4/20/11 20 Physics 122 V Δt v A n tqIΔΔ=4/20/11 21 Physics 122 Δx = v Δt v A n4/20/11 22 Physics 122 Q =Δ(Volume)Δt=AΔxΔtma = Fp− cv a = 0 ⇒ v =FpcFp= AΔP4/20/11 23 Physics 122 I =Δ(charge)Δt=ΔqΔtma = Fe− bv a = 0 ⇒ v =FebFe=
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