M32_KNIG9404_ISM_C32.pdf

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1、32THEMAGNETICFIELDConceptualQuestions32.1.(a)Thesphereisnoteffectedbythemagnet.Glassisnotmagnetic.(b)Thereisnomagneticforcebetweentheglasssphereandmagnetsincemagneticforcesactonmovingchargesandsomemetals.Thereis,however,aweakattractionduetoapolarization

2、ofthechargesifthemagnetismetal.32.2.Itisattracted.Magneticmaterialsareattractedtobothpolesofamagnet.Thisisanalogoustohowneutralobjectsareattractedtobothpositivelyandnegativelychargedrodsbythepolarizationforce.32.3.Yes,ifbothcylindersaremagnetstheywillre

3、pelifoneofthemisturned180°.Ifonlyonecylinderisamagnet,thentheywillstillattractafteroneofthemisturnedaround.32.4.Becausethenorthpolesofthecompassmagnetspointcounterclockwise,themagneticforceiscounter-clockwise.Whenyoupointfingersofyourrighthandcounterclo

4、ckwise,thethumbpointsup.Thus,thecurrentinthewireisoutofthepage.32.5.Themagneticfieldisintothepageontheleftofthewireanditisoutofthepageontherightofthewire.Grabthewirewithyourrighthandinsuchawaythatyourfingerspointoutofthepagetotherightofthewire.Sincethet

5、humbnowpointsdown,thecurrentinthewireisdown.32.6.(a)TheforceonachargemovinginamagneticfieldisdddFqonq=×=vBq(svBin,αdirectionofright-handrule)dApositivechargemovingtotherightwithBintothepagegivesaforcethatisup.(b)Thedirectionoftheforceonanegativechargeis

6、oppositethedirectiondeterminedbytheright-handrule.AdnegativechargemovingupwithBoutofthepagegivesaforcetotheleft.32.7.(a)TheforceonachargemovinginamagneticfieldisdddFqonq=×=vBq(svBin,αdirectionofright-handrule)dApositivechargemovingtotherightwithBdowngiv

7、esaforceintothepage.(b)Thedirectionoftheforceonanegativechargeisoppositethedirectiondeterminedbytheright-handrule.Anychargemovingparalleltothefieldhasnoforceandnodeflection.32.8.(a)TheforceonachargemovinginamagneticfieldisdddFqonq=×=vBq(svBin,αdirection

8、ofright-handrule)ddThemagneticfieldmustbeinaplaneperpendiculartoboththevandFvectors.Usingtheright-handruleforadpositivechargemovingtotheright,theBfieldmustbeoutofthepage.©Copyright2013PearsonEducation,Inc.Allrightsreserved.Thisma