Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download 7.6 Electric Field Strength
Document related concepts
History of electromagnetic theory wikipedia , lookup
Anti-gravity wikipedia , lookup
Weightlessness wikipedia , lookup
Fundamental interaction wikipedia , lookup
Electromagnet wikipedia , lookup
Introduction to gauge theory wikipedia , lookup
Casimir effect wikipedia , lookup
History of quantum field theory wikipedia , lookup
Electromagnetism wikipedia , lookup
Maxwell's equations wikipedia , lookup
Mathematical formulation of the Standard Model wikipedia , lookup
Speed of gravity wikipedia , lookup
Aharonov–Bohm effect wikipedia , lookup
Lorentz force wikipedia , lookup
Field (physics) wikipedia , lookup
Transcript
7.6ElectricFieldStrength Anelectricfieldisaregionofspacewhereachargedobjectwillexperiencean electrostaticforce.Theelectricfieldstrength(E)isthesizeoftheforce(F)feltby aunitcharge: 𝐹 𝐸= 𝑄 (1)!Fromthisequation,whatistheunitforelectricfieldstrengthE? Uniformelectricfield Wecancreateauniformelectricfieldbyapplyingapotentialdifferenceacross twoparallelconductingplatesseparatedbyadistanced.Inthediagram,below, fieldlinesaredrawntoshowtheelectricfield. +V +Q d F 0V Fieldlinesshowtwothings.Thearrowsshowthedirectionaforcewillactona positivechargeplacedatanyposition.Thespacingofthefieldlinestellsusabout therelativestrengthofthefield.Thecloserthelinesaretogether,thestronger thefield. Ifwemovedacharge+Qfrom0Vto+V,wewouldneedtodoworkonthecharge becausetheforceFwouldbeactingdownwards. (2)!Writeanexpressionforworkdone(usingQ,E,d)inmovingthechargefrom 0Vto+V.(Hint:workdoneW=Fd) (3)!TheworkdoneinmovingachargeQfrom0to+Visalsogivenby𝑊 = 𝑄𝑉. SubstituteforWinyourfirstexpressionandsimplifytogetanexpressionforthe electricfieldstrengthEforparallelplates. (4)!Apotentialdifferenceof+100Visappliedacrosstwoparallelplateswitha separationof1cm.Whatistheelectricfieldstrengthinthegap? (5)!Whatistheforceona1.5x10-6Cchargeplacedinthegap? ©2016flippedaroundphysics.com Considerthefollowingsituation: +50V 𝑒 ( 5mm v 0V (6)!Anelectron𝑒 ( isfired,withvelocityv,intoagapbetweentwocharged plates,5mmapart.Sketchthepaththeelectronwilltakeintheelectricfield. Explainyouranswer. (7)!Theelectronhasachargeof-1.6x10-19C.Whatforcewillitexperience? (8)!Theelectronhasarestmassof9.11x10-31kg.Whataccelerationwillit experience? Radialelectricfield ApointchargeQwillproducearadialelectricfieldstrengthgivenbythe expression: 1 𝑄 𝐸= 4𝜋𝜀- 𝑟 / where𝜀- =permittivityoffreespace,r=radialdistancefromchargeQ. (9)!Sketchagraphtoshowhowtheelectricfieldstrengthvarieswithdistancer fromapointpositivecharge.Onthesamegraphdothesameforapointnegative charge. E r ©2016flippedaroundphysics.com Thediagram,left,showsfieldlinesarounda negativepointcharge. (10)!Whydothearrowspointinwards? (11)!Howcanyoutellfromthefieldlinesthat thestrengthoftheelectricfieldincreasesasyou moveinwards? TheforceexperiencebyachargeqisgivenbyF=qE (12)!Showthattheforceexperiencedbyachargeqinaradialelectricfieldis givenbytheexpression: 1 𝑄𝑞 𝐹= 4𝜋𝜀- 𝑟 / whereQisthepointchargeproducingtheradialfield. ©2016flippedaroundphysics.com
