EqnSheet1 - , A r = area vector, equal to area, pointing...

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Physics114 Midterm #1 February 14, 2008 12:30 to 1:30 pm Constants and equations for exam 1. You may detach this page if you wish. Constants: Coulomb’s law constant: k = 8.99 x 10 9 N m 2 /C 2 Permittivity of free space: e 0 = 8.854 x 10 -12 C 2 /(N m 2 ) Charge of one electron: -e = -1.60 x 10 -19 C Coulomb’s law: 2 2 1 0 2 2 1 4 1 r Q Q r Q Q k F πε = = Electric field: Definition: E = F/q; point charge: 2 r Q k E = ; capacitor: E = V/d Electric potential energy (PE) of a charge q in electric field: PE = q V Electric potential: = r d E V r r ; of a point charge: r Q k V = Electric field from electric potential: z V E y V E x V E z y x = = = , , Work: Done by an electric force : W = - (PE final –PE initial ) Done by an external force to move a charge q in electric field: W = q (V final –V initial ) System of charges: ... 3 2 1 + + + = E E E E r r r r sum of point-like charges = 2 r dQ k E continuous charge distribution ... 3 2 1 + + + = V V V V sum of point-like charges = r dQ k V continuous charge distribution Electric flux, Gauss’s law: = Φ A d E E r r
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Unformatted text preview: , A r = area vector, equal to area, pointing perpendicular to area; > E- outflux; < E- influx For uniform field: A E E r r = ; For enclosed charge Q: Q E = Capacitors: Q = C V; Energy: U = Q 2 /C = C V 2 = Q V; Capacitance of a plate capacitor: C = K e A/d Resistors: R = R 1 + R 2 + . .. in series, ... 1 1 1 2 1 + + = R R R in parallel; V = R I; R = r L/A Trigonometry review: ) /( ) ( ) ( ), /( ) ( ) ( ), /( ) ( ) ( adj opp Tan hyp adj Cos hyp opp Sin = = = Pythagorean theorem: (hyp) 2 = (opp) 2 + (adj) 2 Vectors: A or A r and components ( x A , y A ) A + B Nose to tail A points opposite A A B means A + (B) Component = (sign)(magnitude)(trig fn); C = A + B means x x x B A C + = and y y y B A C + = Magnitude of C = | C | = 2 2 y x C C + ; Angle to nearest x-axis: | | | | tan 1 x y C C =...
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