# Shared Flashcard Set

## Details

Electric Current and Magnetism
Resistors, Capacitors, AC & RC circuits, magnetism. Predominantly Formulas
10
Physics
10/16/2010

Term
 Equation for resistance
Definition
 V=RI
Term
 Calculating Resistors in seriesCalculating Resistors in parallel
Definition
 Requ = R1 + R2 + R3...1/Requ = 1/R1 + 1/R2...
Term
 Kirchhoffs Rule
Definition
 Rule 1) assume direction of currentRule 2) Loop Rule: sum up all potential differences (ie Voltage) when going through the closed loop in a circuit = 0
Term
 Capacitors in seriesCapacitors in parallel(Q=CV)(W = 1/2CV^2)
Definition
 1/Cequ = 1/C1 + 2/C2...Cequ = C1 + C2...
Term
 steps for RC circuit and equation
Definition
 Step 1: figure out quatnity of interest (I,V,Q) when t=0Step 2: figure out value at t=infinityStep 3: connect by exponantial using RC as time constantQ(t)= -CV e^(-t/RC) + CV(Vcap(t)= 1/C Q(t) = Vbatt (1-e^(-t/RC))
Term
 a flash for a camera: C = 1200uf. what resistance is needed in the RC circuit if the flas is to charge to 90% of its full charge in 25 sec
Definition
 Q(t) = Qfin (1-e^(-t/RC)Q(t) Q(25)---- = ---- = .9Qfinal Qfin.9 = 1-e^(-25/R1200)ln(e^(-25/R1200) = ln (1-.9)-25sec 25sec------- = ln(.1) => R = - ------ RC 1200uf*ln(.1)
Term
 formula for the magnitude of magnetic force
Definition
 F = qvxB (sin@)
Term
 magnetic feild & work on charge
Definition
 when F is perpendicular to v, no workFcentri = 1/r mv^2 mvr= ---- qB
Term
 electric forcemagnetic force---> v=?
Definition
 F=qEF=qvBqE=qvBE=vBv=E/B
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