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Unformatted text preview: 1 Physics 209, Lecture 9 Todays Topics Current And Resistance (Ch. 27) Motion of Charged Particle In Electric Field (review) Current: Macroscopic and Microscopic Views Resistance: Macroscopic and Microscopic Views Resistance: Macroscopic and Microscopic Views Electrical Power Expected from Preview: Current, current density, drift velocity, Ohm, Ampere, power, Motion Of Charged Particle In The Electric Field Fundamental Formulas: F =q E a = F /m = q E /m v = v i + a t if v i =0, then v = a t A Picture to remember If initially at rest Motion of +q: Same dir. as E From high V to low V Motion of - q: Opposite dir as E E higher potential V lower V +q-q Opposite dir. as E From low V to high V Charge Motion in a Conductor Without electric field: electrons move randomly (thermal motion) | v av |=0, | v | av >0 With electric field applied: electron motion = thermal + drift (directional): | v av |= v drift >0, | v | av >0 i.e. a net charge i....
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