Page 1 of 3 PHYS1120 Exam III review Things to remember for PHYS1110 algebra trig sin cos vector math especially vector addition Fnet ma problems free body diagrams Exam1 and Exam2 Material E fields Gauss s Law voltage capacitors circuits Last part of Chapter 26 RC circuits q C Voltage across a capacitor is always VC An uncharged capacitor has V 0 acts like a wire as short does not resist the flow of current A fully charged capacitor has I 0 acts like an open switch time constant is RC Ch 27 Magnetic fields G K K Fon q q v B This is the definition of B G When both E field and B field are present Ftot G G FE FB N G qE Motion of charge in magnetic field and in velocity selector G K K Fon wire I L B force and torque on a current loop Ch 28 Sources of Magnetic fields Currents cause magnetic fields B fields K K 0 I d A r Biot Savart Law dB 4 r2 10 11 2009 M Dubson PHYS1120 Notes Know what all the symbols mean University of Colorado at Boulder Page 2 of 3 K K v B d A Ampere s Law 0 Ienclosed B L Be able to use Ampere to derive B field outside long straight wire B 0 I 2 r I Ir B field inside long wire B 0 2 2 R B field inside solenoid B 0 n I No need to memorize these formulas know how to derive them modified right hand rule point thumb in direction of straight thing fingers curl in sense of circular thing B field is a vector G G G Btot B1 B2 parallel currents attract anti parallel currents repel Gauss s Law for B fields K K v B da 0 Magnetic monopoles do not exist field of a solenoid permanent magnet acts like solenoid N uniform B out Side View S net atomic atomic current on rim current on rim like solenoid B field comes out of North end End View B field enters South end Ch 29 Faraday s Law Faraday s Law An emf battery voltage is caused by a changing magnetic flux d where is the flux through 1 loop E N loops N dt magnetic flux K K B da emf around a loop E K K v E d A L Be able to use Faraday s Law to derive E field inside or outside a solenoid 10 11 2009 M Dubson PHYS1120 Notes University of Colorado at Boulder Page 3 of 3 Lenz s Law Iinduced creates Binduced in direction that opposes the change in flux Motors and generators Eddy current forces always oppose the motion To prepare for any exam Study my online lecture Notes Review Concept Tests CAPA problems and Tutorial HW Read question and try to remember reasoning that gets to the answer Prepare your formula sheet Prioritize which are the important equations Take the practice exam It is no good to memorize answers You have to understand and remember how you got the answers 10 11 2009 M Dubson PHYS1120 Notes University of Colorado at Boulder
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