Video Summaries Physics Level 3 Electricity DC Circuits Whatyouneedtoknow ($-./-012)Ω InternalResistance ' = )* Kirchhoff’scurrentlaw: 5$ Thecurrententeringa junction,mustequal thecurrentleavinga −5$ 10Ω junction Kirchhoff’svoltagelaw: Voltagesaroundaclosedloopmustaddtozero www.learncoach.co.nz www.learncoach.co.nz 12$ (:)issame emf 47 +5$ 46 45 Video Summaries Capacitors – Part 1 What you need to know Capacitance,',isthe abilitytoholdcharge,(: + + + + + + + + 1234(1) + + + *+*, '= . 12& − ( = '& 1 / = (& 2 0 − − − − −− − − − − −+ − Dielectric isaninsulating(non-conducting)layer betweenplates www.learncoach.co.nz Capacitors – Part 2 Series:lowerscapacitance What you need to know 1 1 1 = + + /0 /2 /4 Charging 12$ 99% 98% 95% 87% Parallel: increasescapacitance 63% /0 = /2 + /4 + 0$ % % 1% % 2% % 3% % 4% TimeConstant:% = 5/ 5% Charged www.learncoach.co.nz www.learncoach.co.nz Video Summaries Inductors – Part 1 ∆ - = ./ ) = − ∆, 1 ( ∆' ! = &' ) = −& 2 ∆, ) = opposingvoltage(0) - = Flux(12) & = Inductance(3) ∆ currentà ∆magneticfieldà opposingvoltageà opposingcurrentà opposingmagneticfieldà … www.learncoach.co.nz Inductors – Part 2 6 12# = What you need to know 7 12# 200Ω 2 63% 87% 95% 98% ∆1 −4 99% 0# 12345- Noopposingvoltage www.learncoach.co.nz What you need to know Aninductoropposeschange www.learncoach.co.nz Video Summaries AC Circuits – Part 1 What you need to know Voltage Capacitor <⁄ cycle(90degrees)behind = -./0 = 1-2.3 Peakvoltage !"# = 1 2 2CDEFDGEC(Ω),LM = 1 NO ×)*+, Inductor <⁄ cycle(90degrees)ahead = 2CDEFDGEC(Ω),LP = NQ www.learncoach.co.nz AC Circuits – Part 2 What you need to know Phase • Inductorandcapacitorreactance,!,(andvoltage,") are180 0 outofphase(opposite). • Thismeanstheycanceleachotherout. ! #% Impedance " ! #$ ! ! • Impedanceis“overallresistance”ofthecircuit • Impedance(')=Resistance(()+Reactance(!) • UseSOHCAHTOAandPythagorastofind Resonance • When!) and!* areequalsizes,theycanceleach otherFULLY.ThismeansNOreactance(' = () • Minimumimpedance(')meansamuchhigher current(" = ,') www.learncoach.co.nz www.learncoach.co.nz