Worksheet 1: Electrostatics

Transcription

1 Wrksht : lctrstatics ) xplain why it is lctrns and nt prtns which ar thught t b xchangd in lctrstatic intractins. ) A strip f actat and a strip f silk ar rubbd tgthr. What can b said abut th chargs bfr and aftr th intractin? lctrns ar lcatd n th xtrir f th atm, whil th psitiv prtns ar lcatd in th nuclus. In frictinal charging nly th xtrir parts f th atms will b in cntact. Th prtns ar als prtctd by layrs f lctrns. ) Hw many lctrns mak up a charg f 00 µ? (6. x ) Th sam numbr f chargs ar prsnt aftr th intractin as bfr. harg is cnsrvd. Th ngativ lctrns ar mrly sparatd frm n atm and attractd t anthr. 6) What prprty maks a mtal a gd cnductr and rubbr a gd insulatr? x 0 x = 6. x x 0 ) Th numbr f lctrns (lmntary chargs) in a culmb is 6. x 0 8. If yu culd cunt 4.0 lctrns pr scnd, and if yu wrkd 8.0 h ach f th 6 days f a yar, hw many yars wuld it tak t cunt this numbr f lctrns? (. x 0 a) s h 8 6. x 0 x x 4.6 x 0 s d a 8 h 6 d x x =. x 0 a 4) What is th charg n a mtal sphr if it has: a) an xcss f.0 x 0 lctrns? b) a dficincy f.0 x 0 lctrns? ( -.6 x 0-4 ) 9.60 x x 0 x = -.6 x x x 0 x = +.6 x 0 Mtals hav fr mbil lctrns whras insulatrs hav lcalizd lctrns. 7) A mtal sphr and a plastic sphr f th sam siz ar supprtd n insulatd stands. ach is nw tuchd t a chargd bdy. mpar th distributin f charg n ach sphr. In th mtal, th charg will rsid vnly n th xtrir surfac as lctrns rpl n anthr. In th insulatr, th charg will b lcalizd whr th bjct was tuchd, but will als rsid n th xtrir surfac. 8) Why d crtain typs f clthing tnd t stick tgthr whn thy ar rmvd frm a clths dryr? In th dryr thy ar charg by frictinal cntact. Sinc thy ar insulatrs, thy d nt grund ut t th mtal surfac f th dryr. 9) What is th significanc f Bnjamin ranklin ( ) in th study f lctrstatics? Why was ranklin's dsignatin f chargs as psitiv and ngativ bttr than th trms vitrus and rsinus? What prblm did ranklin inadvrtntly crat? ranklin cind th trms psitiv and ngativ and invntd a n fluid thry that mr clarly xplaind what happns in static charging. H prfrmd numrus lctrstatic xprimnts including th famus kit-flying xprimnt that shwd that lightning is an lctrstatic phnmna. In dsignating xcss charg as psitiv, ranklin startd th cnvntin that psitiv chargs mv in an lctric fild, which givs th imprssin that it is prtns, nt lctrns, which ar lctrically transfrrd. S tr Dam Pag

2 0) xplain why trucks carrying flammabl fluids drag a chain alng th grund? Th chain acts as a grund t dissipat any static lctric charg which might build up n th truck as a rsult f frictinal charging (mtal t air r rubbr t grund) ) Why is thr a limit t th uantity f charg which can b acuird by a bdy? As an bjct bcms mr ngativ (r psitiv) it will start t rpl lik chargs and attract ppsit chargs. This will chang th bjcts ability t attract furthr similar charg. A vry larg charg will als spntanusly discharg thrugh th air t th grund. ) If yu charg a pckt cmb by rubbing with a silk scarf, hw can yu dtrmin if th cmb is psitivly r ngativly chargd? Yu can tst th charg n any bjct by bringing it cls t an lctrscp f knwn charg. If th lavs start t rpl furthr, th bjct has th sam charg as th lctrscp, and if th lavs start t drps, it has th ppsit charg as th lctrscp. ) If a strngly ngativly chargd bdy is brught nar th trminal f a chargd lctrscp, th lavs cm tgthr. Whn th rd is brught still clsr, but nt tuching, th lavs again divrg. xplain why this might happn. Th inducd charg sparatin will push ngativ chargs dwn int th lavs f a psitivly chargd lctrscp. If th bjct has a sufficintly larg charg, it culd push s many lctrns dwn that th lavs actually bcm ngativly chargd and thn start t rpl n anthr again. 4) Why ds a plastic rulr that has bn rubbd with a clth hav th ability t pick up small pics f papr? Why is it difficult t d n a humid day? Th plastic rulr (ngativly chargd) will caus an inducd charg sparatin in th mlculs f th insulatr papr. Th uppr surfac f th papr will thus b psitivly chargd and sinc unlik chargs attract, it will b pulld tward th plastic rulr. (th unlik chargs bing at a shrtr distanc will hav a strngr frc f attractin than th lik ngativ chargs which rpl at a gratr distanc.) On a humid day, watr mlculs in th air will b attractd t chargd bdis and caus an incrasd gravitatinal frc which wrks against th lctrical attractin. 6) In charging an lctrscp by inductin, why is th fingr withdrawn first, thn th rd? If th rd is rmvd bfr th fingr, chargs will again flw thrugh th grund t nutraliz th lctrscp and as a rsult, thr will b n charg n th lctrscp. 7) Tw idntical mtal sphrs hav chargs f and. Thy ar brught tgthr s thy tuch, and thn thy ar sparatd. a) Hw is th nt charg n th tw sphrs bfr thy tuch rlatd t th nt charg aftr thy tuch? Th nt charg bfr and aftr charging will b th sam. hargs ar mrly rarrangd, thy ar nithr cratd nr dstryd. b) Aftr thy tuch and ar sparatd, is th charg n ach sphr th sam? Why? Sinc thy ar cnductrs, th charg will b ual n th tw sphrs and will b lcatd n th xtrir f th sphrs. 8) ur idntical mtal sphrs hav chargs f A = -8.0 µ, B = -.0 µ, = +.0 µ, and D = +.0 µ. a) Tw f th sphrs ar brught tgthr s thy tuch and thn thy ar sparatd. Which sphrs ar thy, if th final charg n ach n is +.0 µ? charg + charg Sinc = + µ charg + charg = 0µ which wuld indicat chargs B and D b) In a similar mannr, which thr sphrs ar brught tgthr and thn sparatd, if th final charg n ach n is +.0 µ? c) Hw many lctrns wuld hav t b addd t n f th sphrs in part b) t mak it lctrically nutral? charg + charg + charg Sinc = + µ charg + charg + charg = 9µ which wuld indicat chargs A, and D ) an yu suggst an xprimnt that will prv th law f cnsrvatin f charg? araday s Ic Buckt xprimnt shws that charg is cnsrvd in frictinal intractins S tr Dam Pag

3 9) Dscrib what happns at ach f th stags in charging a nutral lctrscp ngativly using a psitivly chargd glass rd. If an ppsit charg is prmanntly givn t th lctrscp, charg by inductin is indicatd. In th first stag a ngativ charg is brught nar th lctrscp and an inducd charg sparatin ccurs n th lctrscp in which th lavs and far sid f th ball ar ngativly chargd and th nar sid f th ball is psitivly chargd. Thn th ball is mmntarily grundd n th far sid and lctrns lav t th grund. Whn th grund is rmvd, lctrns cannt rturn. Whn th charging bdy is subsuntly rmvd, thr is a nt psitiv charg n th lctrscp. Th lavs and all surfacs f th lctrscp ar psitivly chargd. 0) xplain why th frc f rpulsin is th nly sur tst f th sign f an lctric charg. Tw bdis culd b attractd ithr by an inducd charg sparatin r by unlik chargs, but can nly b rplld bcaus th chargs ar th sam. If tw bdis attract, yu can t tll whthr th scnd bdy was nutral r f an unlik charg. ) A chargd bdy whn brught nar a suspndd pith ball will first attract it. If th chargd bdy and th pith ball thn tuch, th ball will b rplld. xplain. In th first cas, thr is an inducd charg sparatin n th pith ball whrby th far sid f th ball has a lik charg and th nar sid has an unlik charg du t th mtin f lctrns. As it is a cnductr, lctrns ar fr t mv thrughut th surfac f th pith ball. Th nar sid is at a shrtr distanc, thrfr th attractiv frcs f th unlik chargs will b strngr than th rpulsiv frcs f th lik chargs. Upn tuching (cnductin), lctrns will b transfrrd frm th mr ngativ bdy t th lss ngativ bdy and th lik chargs will subsuntly rpl. Wrksht : Applicatins f harging ) mpltly xplain th prcss by which an lctrstatic prcipitatr rmvs fly ash frm industrial smk. Includ an apprpriat diagram. In th lctrstatic prcipitatr, th larg ash particls ar first rmvd by passing thrugh a mchanical filtr such as asbsts. Th smallr particl thn pass thrugh an lctrically chargd grid which chargs th small ash particls with a crnal discharg frm th clsly placd mtallic msh. Th particls ar thn rmvd frm th air whn thy pass thrugh a scnd grid with ppsit charg. As unlik chargs attract, th ash will stick t th scnd grid, and can b rmvd by washing th grid at sm latr tim. ) Stat th stps invlvd in prducing a Xrx cpy. Spcify th typs f charging invlvd at ach stp (whr apprpriat) ) Th slnium drum is chargd n its surfac thrugh a crnal discharg frm th crtrn. (small sharp pints which pass charg t th drum. ) A halgn light rflcts frm th t b cpid surfac t th drum and dischargs th drum whrvr th light cntacts (i.. nt whr th print is) th drum. ) Small tnr bads (insulatrs) ar attractd t th drum by an inducd charg sparatin and stick t th drum 4) A scnd crtrn, blw th papr attracts th tnr nt th papr, whr it sticks lctrstatically ) Th tnr and papr pass thrugh a hat salr whr th small plastic bads ar mltd nt th papr and th papr is dischargd. ) Why is a an d Graff gnratr lss dangrus than an lctrical utlt bx in yur hm? Th an d Graff gnratr (althugh it dvlps a larg charg) dischargs fr nly a fractin f a scnd. Th wall utlt, althugh at a much smallr vltag (i.. amunt f charg) dischargs cntinually and causs muscl tissu t cntract and rmain cntractd 4) xplain th prcss by which a lightning strik is gnratd. Spcifically stat th typ charging invlvd and lctrn mtin at ach stp. Includ apprpriat diagrams. In th summr, thr is gratr hating f air just abv th grund than highr up in th atmsphr. Th httr air riss in updrafts which tunnl up thrugh th clr air. This rsults in frictinal charging btwn watr mlculs in diffrnt stats (slid, grmml - smislid, liuid). Th bttm part f th clud bcms ngativly chargd as a rsult, th middl part psitivly chargd and th uppr part f larg cluds ngativly chargd. In turn, th ngativ bttm f th clud rpls lctrns in th grund, causing an inducd psitiv charg n th grund. Th highr pintd bjcts n th grund thn build up stp ladrs twards th cluds (aras f psitivly chargd pckts f air) and th clud ngativly chargd stp-ladrs which mv twards th grund. Th lightning bcms luminus whn th tw ladrs mt smwhr in btwn and lctrns mv t th grund. Thr is a furthr grund discharg as th lctrns mv ut latrally thrugh th psitiv grund, nutralizing th grund charg. S tr Dam Pag

4 ) Jan 00 - In a physics dmnstratin, a studnt inflats a balln by blwing int it. Th nd f th balln is thn tid. Th balln is rubbd with fur and dvlps an lctrstatic charg. Th balln is placd against th ciling and rlasd. It rmains "stuck" t th ciling. Th tachr thn prsnts th fllwing challngs t th studnts: -xplain hw th balln rcivd th lctrstatic charg -xplain why th balln is attractd t th ciling -prvid a prcdur that wuld dtrmin if th charg n th balln is psitiv r ngativ. Includ a list f any additinal uipmnt ndd. -prvid a prcdur that culd b usd t dtrmin if thr is a rlatinship btwn th amunt f rubbing and th amunt f charg dvlpd n an inflatd balln. Includ a list f any additinal uipmnt ndd. Using cncpts frm Physics 0, prvid a rspns t ach f th tachr's challngs. Marks will b awardd fr th physics usd t slv this prblm and fr th ffctiv cmmunicatin f yur rspns. Th balln bcms ngativly chargd thrugh frictinal charging whn th balln attracts lctrns away frm th fur. Th charg n th balln culd b cnfirmd with an lctrscp f knwn ngativ charg. If th balln is ngativly chargd, th lavs f th lctrscp will sparat furthr as th balln is brught cls t, but ds nt tuch th ball f th lctrscp. Th ngativ balln thn inducs a charg sparatin in th wall by rplling lctrns within th mlculs f th wall. Th nar surfac f th wall gains a psitiv charg and th far surfac f th wall a ngativ charg. Sinc th nar surfac is clsr t th balln this lctrical attractin is gratr than th rpulsin f th tw ngativ surfacs. T dtrmin if thr is a rlatinship btwn th amunt f rubbing and th amunt f charg dvlpd n th balln: Manipulatd variabl: numbr f rubs spnding variabl: sparatin f lctrscp lavs ntrl variabl: distanc f th balln frm th lctrscp. Hw t chang th manipulatd variabl: D a sris f trials in which th numbr f rubs f th balln is stadily incrasd vr th trials. Hw t masur th rspnding variabl: Masur th angl f sparatin btwn th lavs f th lctrscp. A gratr angl indicats a gratr lctrical frc. (diagram) Wrksht : ulmbic (lctrical) rcs ) Tw studnts ar sitting.0 m apart. On studnt has a mass f 70.0 kg and th thr has a mass f.0 kg. What is th gravitatinal frc btwn thm? (.08 x 0-7 ) Gm m = g 7 (6.67 x 0 )(70)() g = =.08 x 0 g (.0) 7 ) What gravitatinal frc ds th mn prduc n th arth if th cntrs f th arth and mn ar.88 x 0 8 m apart and th mn has a mass f 7.4 x 0 kg? (.94 x 0 0 ) Gm m = g 7 4 (6.67 x 0 )(7.4 x 0 )(.98 x 0 ) g 8 = =.94 x 0 g 0 (.88 x 0 ) ) alculat th lctric frc btwn tw pint chargs f 4.00 µ and.00 µ whn thy ar.00 cm apart. (.70 x 0 ) k = = (8.99 x 0 )(4.0 x 0 )(.0 x 0 ) =.70 x 0 (0.0) 4) Tw pints f ual charg prduc an lctric frc n ach thr f.40 x 0 - whn placd.00 x 0 - m apart. What is th charg n ach pint? (.94 x 0-7 ) 9 k.4 x 0 ( x 0 ) 8.99 x 0.94 x 0 7 S tr Dam Pag 4

5 ) Tw pint chargd bjcts prduc an lctric frc n ach thr f 4. x 0 -. What is th lctric frc if th charg n bth bjcts tripl and th distanc btwn thm dubls? (.0 x 0 - ) k nw () = k ld 9 nw = ld 4 9 nw = (4. x 0 ) 4 nw =.0 x 0 6) Thr pint chargd bjcts ar placd in a lin as shwn in th diagram. alculat th magnitud f th nt lctric frc n th cntr charg du t th thr tw chargs. (. x 0 - ) Th nt lctric frc will b th vctr sum f th tw frcs acting n th charg. Sinc th thr tw chargs ar bth psitiv, ths frcs will b pushing in ppsit dirctins as lik chargs rpl () = () = k 8.99 x 0 (.0 x 0 ) (0.40) () = 0.47 ast 9 6 () = 0.7 Wst 7) Tw small sphrs hav th sam mass and vlum. On f th sphrs has a charg f 4.00 µ and th thr sphr has a charg f -.00 µ. If ths tw sphrs ar brught int brif cntact with ach thr and thn sparatd t a distanc f.00 x 0 - m, what is th lctric frc btwn thm at this distanc? (.0 x 0 - ) Whn th tw sphrs tuch, th ttal charg is shard btwn th sphrs Q + Q 4 x x 0 = 6 =. x 0 ach = = 6 6 k 8.99 x 0 (. x 0 ) ( x 0 ) 9 6 =. x 0 rpulsiv 8) Thr pint chargd bjcts ar placd at th crnr f a right-angl triangl as shwn in th diagram. alculat th magnitud f th nt lctric frc n th charg markd with th x du t th thr tw chargs. (.0 x 0 - ) Whn chargs and ar at right angls t charg, th nt frc can b fund using a Pythagran sum f th vctr frcs acting n. Sinc all th chargs ar psitiv and lik chargs rpl, will b nrthward and will b t th ast. = + - (nt) () () (nt) = nw =. x 0 Wst S tr Dam Pag

6 () = () = x 0 (.0 x 0 )(4.0 x 0 ) () = () = nt nt nt k = + () () (0.60) = ( ) + ( ) ϑ = tan ϑ = tan ϑ = 0.0 ( ) () =. f =.0 x f 9) Tw small sphrs, ach with a mass f.00 x 0 - kg, ar placd.0 x 0 - m apart. On sphr has a charg f -.00 µ and is fixd in psitin. Th thr sphr has a charg f -.00 µ but is fr t mv withut frictin. What is th initial acclratin du t th lctric frc n th sphr that is fr t mv? (.0 x 0 4 m/s ) = = k x 0 (-.0 x 0 )(-.0 x 0 ) (0.) = rpulsiv Sinc th lctric frc is th nly frc n th bjct, it is th nt frc. = nt a = m a =.0 x 0 a =.0 x 0 4 m away frm th thr charg s 0) Th drawing shws thr pint chargs fixd in plac. Th charg at th crdinat rigin has a valu f = µ; th thr tw hav idntical magnituds. but ppsit signs: = -.00 µ and = +.00 µ. a) Dtrmin th nt frc (magnitud and dirctin) xrtd n by th thr tw chargs. b) If had a mass f.0 g and it was fr t mv, what wuld b its acclratin? Th nt frc will b th vctr sum f th tw frcs () and (). Sinc ths vctrs ar at nn-right angls, th x and y cmpnnts nd t b addd sparatly t dtrmin th nt frc. k () = x 0 (8.0 x 0 )(.0 x 0 ) () = (.) () = at f dirctin dtrmind as unlik chargs attract () = at f W dirctin dtrmind as lik chargs rpl S tr Dam Pag 6

7 () + () ( 0.78 cs(), +78 sin()) (nt) ( 0, ) (nt) ( cs(), +78 sin()) = 0.66 rth ) Supps that w plac thr small, ually chargd mtal sphrs A, B and s that A is. cm wst f B and is.0 cm suth f B. It is knwn that xrts a frc f 4.0 µ n B. = + nt nt (AB) (B) = (.8 x 0 ) + (4.0 x 0 ) 6 nt = 4.9 x 0 ϑ = tan ϑ = tan ϑ (B) (AB) 4.0 x 0.8 x 0 = f nt = 4.9 x f a) What frc ds A xrt n B? ( AB =.8 µ) b) What is th magnitud and dirctin f th nt frc n B? (4.9 µ at f ) In this ustin, all th frcs ar rpulsiv sinc lik chargs rpl. Th nt frc will b th vctr sum f th tw frcs (AB) and (B). Sinc ths vctrs ar at right angls, a Pythagran sum can b usd t find th nt frc. k (AB) (0.) (0.) = = (B) k (0.) (0.) (0.) 6 6 (AB) = (B) = 0.69 x 0 (B) =.8 x 0 (0.) Sinc is th nly frc, it is als th nt frc = nt nt a = m 0.66 a = 0.00 m a = s S tr Dam Pag 7

8 ) Tw ually chargd idntical cnducting sphrs A and B rpl ach thr with a frc f 0.0 µ. Anthr idntical unchargd sphr,, is tuchd t A and thn mv nxt t but nt tuching B a) What is th lctric frc n A nw? (0. µ (lft r wst) b) What is th nt lctric frc with dirctin n if it is nw mvd halfway btwn A and B? ( nt = 0.0 µ twards A) Whn th tw cnductrs ar tuchd, A and will shar th charg ually btwn th tw sphrs QA + Q + 0 = = Th charg whr B was lcatd will nw b + If is lcatd half way btwn B and A, th nt frc will b th linar vctr sum f A and B k k A B = = and = = ld k ld k A = ld = 0.0 µ ast as lik chargs rpl and B = ld = 0.40 µ Wst as lik chargs rpl nt = A + B µ µ µ nt = nt = 0.0 Wst ) Thr ually chargd mtal sphrs ar lcatd as shwn k nw = = ld k 4 nw = ld = (0.0 µ ) = 0. µ 4 4 Th dirctin will b Wst sinc lik chargs rpl Th lctric frc xrtd by A n B is.98 µ a) What lctric frc ds xrt n B? (.9 µ) b) What is th magnitud and dirctin f th nt frc n B? (. µ at 4 f ) S tr Dam Pag 8

9 k = = 4 B AB k 6 B = 4 AB = 4(.98 x 0 )=.9 µ rth as lik chargs rpl Th nt frc can b fund frm a Pythagran sum f th frcs B and AB sinc th chargs a at right angls t B r 4) A studnt prfrmd an xprimnt that vrifid ulmb's Law f lctrstatics by masuring th rpulsin btwn tw chargd sphrs, A and B, as a functin f th sparatin f th sphrs. Th sphrs wr idntical in siz and mass. Th masurmnts ar shwn in th tabl f valu sand plttd n th graph blw. (Jan 99) = + nt AB B 6 6 nt = (.98 x 0 ) + (.9 x 0 ) nt =. x 0 ϑ = tan ϑ = tan ϑ (B) (AB).9 x x 0 = 76 f 6 6 nt =. x 76 f a) Shw that th rsults vrify ulmb's Law by manipulating th data and prviding a nw tabl f valus that, whn plttd, will prduc a straight-lin graph. b) Plt th nw data with th rspnding variabl n th vrtical axis. c) alculat th slp f yur graph. (7.9 x 0 - m ) d) Using th slp valu, r anthr suitabl avraging tchnius dtrmin th charg n sphr B if th charg n sphr A is.08 x 0-7. (.9 x 0-6 ) ) Dtrmin th magnitud f th frc btwn sphrs A and B whn thy ar at a distanc f.00 m apart. Us th hypthtical valu f.00 x 0-6 fr th charg n sphr B if yu wr unabl t dtrmin th actual valu. (.0 x 0 - ) S tr Dam Pag 9

10 L = sparatin (m) L = rc () L = /sparatin (/m ) L /sparatin (/m ).0 x k = = (8.99 x 0 )(.08 x 0 )(.9 x 0 ) = =.0 x 0.00 Wrksht 4: lctric ilds ) What is an lctric fild? An lctric fild is th ara arund a chargd particl in which th chargd particl can xrt a frc n thr chargd particls. ) What ar th similaritis btwn an lctrical fild and a gravitatinal fild? What ar th diffrncs btwn ths tw typs f filds? Similaritis: Bth ar filds that ccur at a distanc, and bth ar invrsly rlatd t th suar f th distanc btwn th cntrs f th bjcts invlvd. Diffrncs: Gravity is dirctly rlatd t th prduct f tw masss and lctrical is dirctly rlatd t th prduct f tw chargs. Whr gravity can nly b attractiv, lctrical frcs ar bth attractiv (unlik chargs) and rpulsiv (lik chargs), Ling(ax+b) L, L, Y a = 7.9 x 0 - m b =.0 x 0 - r = min max scl Windw x[ ] y[ ] By ulmb s Law k =, thrfr = slp = k slp and hnc k (8.99 x 0 9 )(.08 x 0 7 ) ) Draw th shap f th fllwing filds: a) arund a psitiv pint charg. b) btwn a psitiv and a ngativ pint charg c) btwn a vrtical psitiv and a vrtical ngativ plat. d) insid a ngativly chargd, circular cnductr. a) b) c) d) 6.9 x 0 S tr Dam Pag 0

11 4) What ar th tw mthds t calculat th strngth f an lctric fild? k = using th cntral charg which crats th fild = using th frc flt by a charg which cms int th fild Wrksht : lctric ild Intnsity ) What is th lctric fild strngth 7.0 x 0 - m frm a 8.00 µ chargd bjct? (.8 x 0 /) k = = 9 6 (8.99 x 0 )(8.0 x 0 ) (7. x 0 ) =.8 x 0 4) If an alpha particl xprincs an lctric frc f 0.0 at a pint in spac, what lctric frc wuld a prtn xprinc at th sam pint? (0. ) -9 k (.60 x 0 ) p = -9 α k (.0 x 0 ) = p α = (0.0) p = 0. p ) What is th initial acclratin n an alpha particl whn it is placd at a pint in spac whr th lctric fild strngth is 7.60 x 0 4 /? (.66 x 0 m/s ) = 4 9 = (7.60 x 0 )(. x 0 ) =.4.. x 0 4 ) alculat th gravitatinal fild strngth n th surfac f Mars. Mars has a radius f.4 x 0 6 m and a mass f 6.7 x 0 kg. (.6 /kg) Gm a = g a = (6.67 x 0 )(6.78 x 0 ) g 6 a =.6 g kg (.4 x 0 ) ) At a pint a shrt distanc frm a 4.60 x 0-6 chargd bjct, thr is an lctric fild strngth f.7 x 0 /. What is th distanc t th chargd bjct prducing this fild? (.88 x 0 - m) As th lctric frc is th nly frc prsnt, it is th nt frc = a = m.4.. x 0 a = 6.67 x m a =.6 x 0 s nt = k = x 0 (4.6 x 0 ).7 x 0 = 0.88 m 6) alculat th lctric fild strngth mid-way btwn a S tr Dam Pag

12 4.0 µ chargd bjct and a -4.0 µ chargd bjct if th tw chargd bjcts ar.00 x 0 - m apart. (.9 x 0 6 /) Th nt lctric fild will b th vctr sum f th fild frm and th fild frm, whr th dirctins f th filds ar dfind by a psitiv tst charg k = x 0 (4. x 0 ) = (. x 0 ) = x 0 right (s diagram) = x 0 right (s diagram) = + nt nt = ( x 0 ) 6 nt =.9 x 0 right 7) alculat th lctric fild strngth mid-way btwn a.0 µ chargd bjct and a 6.0 µ chargd bjct if th bjcts ar 8.0 x 0 - m apart. (.7 x 0 /) Th nt lctric fild will b th vctr sum f th fild frm and th fild frm, whr th dirctins f th filds ar dfind by a psitiv tst charg k = x 0 (.0 x 0 ) = =.68 x 0 ast (s diagram) =.7 x 0 Wst (s diagram) nt nt =.68 x x 0 nt =.7 x (4.0 x 0 ) = Wst 8) alculat th magnitud and dirctin f th lctric fild at th cntr f a suar with 0.0 cm sids if th crnrs takn in cuntr-lckwis rtatin frm tp right, hav chargs f +.00 µ, +.00 µ, +.00 µ and µ. Th suar is lvl with th hrizntal. (8.99 x 0 4 / tward th tp f th suar) Th distanc frm ach f th chargs t th pint can b dducd frm th Pythagran rlatinship. = x + y = = m ach f th chargs is at a 4 angl t th pint du t th sids f th triangl in th Pythagran rlatinship bing ual. S tr Dam Pag

13 Sinc th filds cratd by th thr chargs ar nt all at right angls t th pint, th nt lctric fild will b th vctr sum f th fild frm,, and 4, xprssd as cmpnnts in th x and y dimnsins whr th dirctins f th filds ar dfind by a psitiv tst charg. 6 nt =.09 x 0 rth 9) A chargd sphr having.0 f xcss psitiv charg is lcatd 0.0 m du nrth f a scnd sphr having 0.0 f xcss psitiv charg. What is th nt lctrical fild intnsity at th pint(s) 0.0 m frm th first and 40.0 m frm th scnd sphr? (6. x 0 7 / 60.8 f ) = x 0 (.0 x 0 ) = 6 =.798 x 0 4 S f W 6 =.96 x 0 4 S f = k (0.0707) 6.94 x 0 4 f 6 4 = 7.9 x 0 4 f W Using cmpnnt tchnius t rslv th nt lctric fild. x 6 6 = (-.798 x 0 cs 4,.798 x 0 sin 4) 6 6 = (.96 x 0 cs 4,.96 x 0 sin 4) 6 6 = (.94 x 0 cs 4,.94 x 0 sin 4) = (-7.9 x 0 cs 4, 7.9 x 0 sin 4) nt = ( 0,.09 y 6 x 0 ) Sinc this is a, 4, triangl, it must hav a right angl as indicatd. a ϑ 0 40 φ ϑ = φ =. - ϑ = tan φ = 90 -ϑ - = tan = Sinc th filds cratd by th tw chargs ar in a crdinat plan, th nt lctric fild will b th vctr sum f th fild frm and, xprssd as cmpnnts in th x and y dimnsins whr th dirctins f th filds ar dfind by a psitiv tst charg. S tr Dam Pag

14 A A = k = x 0 (.) (0) 7 A =.497 x S f 7 B = x 0. f 0) Jun 89. All thr bjcts ar psitivly chargd Using cmpnnt tchnius t rslv th nt lctric fild. x y 7 7 A = ( x 0 cs6.869, x 0 sin 6.869) B = ( x 0 cs., x 0 cs.) 7 nt = (.7... x 0, x 0 ) nt = nt(x) + nt(y) ϑ = tan nt = (.7... x 0 ) + ( x 0 ) ϑ = tan 7 7 nt = 6. x 0 ϑ = nt = 6. x 0 at 9. f nt(y) nt(x) x x 0 a) Givn that th chargs n A and B ar ach f magnitud.00 x 0-6, and that th charg n is f magnitud 4.00 x 0-6, dtrmin th magnitud and dirctin f th nt frc acting n bjct A. Illustrat th answr t part with an apprpriat sktch. (7. at. S f W) b) If th mass f A is. x 0 - kg, what is th initial acclratin f A? (. m/s at. S f W) d) Us a vctr sktch t draw in th apprximat dirctin f th lctric fild intnsity at pint P which is half way btwn B and. Th nt frc will b th vctr sum f BA and A whr th frcs ar at right angls and hnc th nt frc can b dtrmind using a Pythagran sum. BA = k x 0 (.0 x 0 )(.0 x BA = BA A =.47 Wst = 9.96 Suth (0.06) 0 ) Whr th dirctins f th frcs ar dtrmind frm th law f chargs that lik chargs rpl. S tr Dam Pag 4

15 + = tan A t = BA A ϑ BA t = (.47) + (9.96) ϑ = tan t = 7. ϑ =. 0 t = 7. at. S f W Th vltag at P will b th scalar sum f th thr vltags. k = = x 0 (.0 x 0 ) 0.07 =. x 0 As th lctric frc is th nly frc prating, it is als th nt frc = a = m 7. a =. x 0 a =. x 0 4 nt m at. S f W s = -. x 0 = -.6 x 0 = + + nt =. x x x 0 nt = -.0 x 0 nt Wrksht 6: lctrical Ptntial and ild Ptntial: Pint hargs ) Thr chargs ar at th crnrs f a rctangl as shwn blw: ) What is th ptntial at a distanc f 6.0 cm frm a. µ charg? (.7 x 0 ) k = = x 0 (. x 0 ) 0.06 =.7 x 0 ) Thr chargs ar alng a lin as shwn blw: ind th ptntial at pint P. (-.0 x 0 ) ind th ptntial at pint P. (4.4 x 0 ) Th distanc frm charg t th pint can b dducd frm th Pythagran rlatinship. = x + y = = 0.0 m S tr Dam Pag

16 Th vltag at P will b th scalar sum f th thr vltags. k = = x 0 (.0 x 0 ) =. x 0 = x 0 =.99 x 0 = + + nt =. x nt = 4.4 x 0 nt x x 0 6) What is th lctrical ptntial nrgy f an lctrn at a distanc f.00 x 0-0 m frm a prtn? (-.0 x 0-8 J, ngativ indicats attractin) k = l = x 0 (.60 x 0 )(-.60 x 0 ) l 0 8 =.0 x 0 J l.0 x 0 7) What is th ptntial nrgy f a prtn half way btwn tw alpha particls sparatd by.00 x 0-4 m? (.84 x 0 - J) 4) A -. µ charg is 4.0 cm t th lft f a.0 µ charg. What is th fild ptntial at a pint.0 cm t th right f th -. µ charg? (-.6 x 0 6 ) Th vltag at P will b th scalar sum f th tw vltags. k = = x 0 (-. x 0 ) 6 = -.46 x 0 6 =. x 0 = + nt nt nt 0.00 = -.46 x 0 +. x 0 = x ) What is th fild ptntial at a distanc f.00 x 0-0 m frm a prtn? (4.4 ) Th lctrical ptntial nrgy at P will b th scalar sum f th tw nrgis. k = l = x 0 (.0 x 0 )(.60 x 0 ) l 4 = 9.0 x 0 J l 4 = 9.0 x 0 J l = + lnt l l 4 = (9.0 x 0 ) lnt =.84 x 0 J lnt.00 x 0 k = = x 0 (.60 x 0 ) 0 = x 0 S tr Dam Pag 6

17 8) Hw much ds th ptntial nrgy f a 0.00 µ charg in th fild f a.0 µ chargd bjct chang whn it is mvd frm = 4 cm away t = cm? (6.0 x 0 - J) = l l(final) l(initial) f - k k = - l = k - l f i = 8.99 x 0 (.0 x 0 )(.0 x 0 ) l = 6.0 x 0 J l i 9) 4.40 x 0 - J f nrgy is usd in mving a.00 µ charg at a cnstant spd frm pint A t pint B. If A and B ar.4 cm apart, what is th ptntial diffrnc btwn A and B? (4.7 ) Λ = 4.40 x 0 =.00 x 0 = Wrksht 7: lctrical Ptntial and ild Ptntial: Plats ) Tw paralll plats ar cnnctd t a.0 battry. If th plats ar 9.00 x 0 - m apart, what is th lctric fild strngth btwn thm? (. x 0 /m) = d = ) Th lctric fild btwn tw paralll plats is.0 x 0 /m. If th ptntial diffrnc btwn th plats is.0 x 0, hw far apart ar th plats? (4.0 x 0 - m) d = 00 d =.0 x 0 d = 4.0 x 0 m ) What is th valu f th ptntial nrgy f an alpha particl in th lctric fild btwn paralll plats if it is right nxt t th psitiv plat at 00.0? (.60 x 0-6 ) = l 9 = 00(. x 0 ) l 6 =.6 x 0 J l 4) If an lctrn is.00 cm away frm th ngativ plat in a.00 x 0 / lctric fild btwn paralll plats which ar 8.00 cm apart, what is th valu f th lctrn s ptntial nrgy? (9.60 x 0-8 J) = d =.0 x 0 (0.080) = 80 An lctrn that is.00 cm away frm th ngativ plat still rtains ¾ f its ptntial nrgy in th 8.00 cm fild btwn th plats. = l 9 = 60(.6 x 0 ) l 8 = 9.60 x 0 J l =. x 0 m S tr Dam Pag 7

18 ) What is th fild intnsity btwn tw paralll plats if an lctrn is halfway btwn th plats? Th plats hav a ptntial f 70 and ar 0.0 cm apart. (7.0 x 0 /) is cnstant btwn paralll plats f ppsit charg = d 70 = 0.0 = 7.0 x 0 m 6) What is th ptntial diffrnc btwn tw paralll plats.00 cm apart that prducs an lctric frc f.0 x 0 - n an bjct cntaining a charg f.00 x 0-6 whn it is placd btwn th plats? (8.7 x 0 ) = d. x 0 = (0.00) 6.0 x 0 = 87. 7) Th lctric fild strngth btwn tw paralll plats is 9. x 0 /m whn th plats ar 7.0 cm apart. What wuld th lctric fild strngth b if th plats wr.0 cm apart? (.8 x 0 /m) nrgy is cnsrvd as lctrical ptntial is cnvrtd t kintic nrgy. Σ = Σ l nw ld = k k k = k(nw) = k(ld) k(nw) = nw ld k(ld) 9.00 x 0.00 x 0 7 nw = (4. x 0 ) 7 =.6 x 0 nw 8) A hlium nuclus, with a mass f 6.6 x 0-7 kg, is insrtd btwn tw chargd paralll plats. Th ptntial diffrnc btwn th plats is. x 0, and th distanc btwn th plats is. cm. What tim is ruird fr th hlium nuclus t rach th ngativ plat? nt ) a = sinc is th nly significant frc m a = m a = m a = d m 9 a =. x 0 (. x 0 ) (0.0)(6.6 x 0 7 ) m a =.06 x 0 s ) d = vit + at sinc v i = 0 t = t = d a (0.0).06 x 0 7 t =.84 x 0 s 9) What is th ptntial diffrnc btwn tw paralll chargd plats that ar 7.0 cm apart if a frc f.0 x0-4 is ndd t mv an alpha particl frm th ngativ plat t th psitiv plat?(.4 x 0 4 ) = d 4. x 0 = (0.07) 6. x 0 4 =.4 x 0 0) An alpha particl is placd btwn tw hrizntal paralll chargd plats that ar.00 cm apart. Th ptntial diffrnc btwn th plats is.0. a) What is th lctric frc acting n th alpha particl? (.9 x 0-6 ) b) What is th gravitatinal frc acting n th alpha particl? (6. x 0-6 ) c) Assuming that th lctric frc and th gravitatinal frc ar acting in ppsit dirctins, what is th nt frc acting n th alpha particl? (.9 x 0-6 ) S tr Dam Pag 8

19 d) What is th acclratin f th alpha particl? (.88 x 0 0 m/s ) ) What ptntial diffrnc wuld b ruird btwn th plats in rdr that th alpha particl bcms suspndd? (4.09 x 0-9 ) a) b) c) d) Bth and ar cnstant btwn paralll plats f ppsit charg = = d 9 = (. x 0 ) =.9 x 0 = mg g 7 = 6.67 x 0 (9.8) g = 6. x 0 g = + - nt l g nt =.9 x x 0 6 nt =.9 x 0 nt a = m.9 x 0 a = 6.67 x 0 a =.88 x m s ) If a particl wr suspndd btwn th plats thn frcs wuld b balancd. l = g = mg d mgd = = x 0 (9.8)(0.00) = 4.09 x 0. x Wrksht 8: Wrk and nrgy in lctric ilds ) A prtn is rlasd.0 x 0 - m frm th cntr f a 6.4 x 0-8 chargd sphr. What is th spd f this prtn whn it is 0.0 m frm this cntr? (7.4 x 0 m/s) nrgy is cnsrvd as sm f th lctrical ptntial nrgy is cnvrtd t kintic nrgy Σ = Σ = + l k l k k = mv + v = - v = k m m v = 7.4 x 0 s (8.99 x 0 )(.6 x 0 )(6.4 x 0 ) x 0 x ) Th cntrs f tw alpha particls ar hld. x 0 - m apart whn thy ar rlasd. alculat th spd f ach alpha particl whn thy 0.7 m apart. (.4x 0 4 m/s) S tr Dam Pag 9

20 nrgy is cnsrvd as sm f th lctrical ptntial nrgy is cnvrtd t kintic nrgy f th tw alpha particls Σ = Σ = + l k l k k = () mv + k m v = (8.99 x 0 )(. x 0 ) v = x 0. x m v =. x 0 s ) An alpha particl gains.0 x 0 - J f kintic nrgy. Thrugh what ptntial diffrnc was it acclratd? (4.69 x 0 ) nrgy is cnsrvd as th lctrical ptntial nrgy is cnvrtd t kintic nrgy Σ = Σ l = k k = k. x 0 =. x 0 9 = 4.69 x 0 4) A prtn is acclratd by a ptntial diffrnc f 7.0 x 0. What is th chang in kintic nrgy f th prtn? (. x 0-6 J) nrgy is cnsrvd as th lctrical ptntial nrgy is cnvrtd t kintic nrgy Σ = Σ l = k k 9 k = 7. x 0 (.6 x 0 ) 6 =. x 0 J k ) What maximum spd will an alpha particl rach if it mvs frm rst thrugh a ptntial diffrnc f 7.0 x 0? (8.0 x 0 m/s) nrgy is cnsrvd as th lctrical ptntial nrgy is cnvrtd t kintic nrgy Σ = Σ l = k mv v = v = m 9 (7. x 0 )(. x 0 ) 6.67 x 0 7 m v = 8.48 x 0 s 6) A prtn is placd in an lctric fild btwn tw paralll plats. If th plats ar 6.0 cm apart and hav a ptntial diffrnc btwn thm f 7. x 0, hw much wrk is dn against th lctric fild whn th prtn is mvd.0 cm paralll t th plats? (0) If th prtn mvs hrizntally, thr is n chang in its ptntial nrgy. Hnc, thr is n wrk dn. 7) In th abv ustin, hw much wrk wuld b dn against th lctric fild if th prtn was mvd.0 cm prpndicular t th plats? (6.0 x 0-8 J) If th charg mvs vrtically.0 cm ut f a ttal f 6.0 cm, thn it will crss half f th vltag btwn th plats. rm th wrk-nrgy thrm, th wrk dn is uivalnt t th chang in ptntial nrgy. S tr Dam Pag 0

21 W = l W = 9 W = 7.(.6 x 0 ) 8 W = 6.0 x 0 J 8) A chargd particl was acclratd frm rst by a ptntial diffrnc f 4.0 x 0. If this particl incrasd its kintic nrgy t.00 x 0-7 J, what ptntial diffrnc wuld b ndd t incras th kintic nrgy f th sam particl t 9.00 x 0-7 J? (.6 x 0 ) nrgy is cnsrvd as lctrical ptntial is cnvrtd t kintic nrgy. Σ = Σ l nw ld = k k k = k(nw) = k(ld) k(nw) = nw ld k(ld) 9.00 x 0.00 x 0 7 = (4. x 0 ) nw 7 =.6 x 0 nw 9) An alpha particl with an initial spd f 7. x 0 4 m/s ntrs thrugh a hl in th psitiv plat btwn tw paralll plats that ar 9.00 x 0 - m apart as shwn in th diagram. nrgy is cnsrvd as sm f th lctrical ptntial nrgy is cnvrtd t kintic nrgy Σ = Σ + = k l k mv mv + d - mdv v = md v = -9-7 (.7 x 0 )(. x 0 ) x 0 (0.090)(7. x x 0 ) x 0 (0.090) 4 m v = 8. x 0 s 0) An lctrn with a spd f.0 x 0 m/s ntrs thrugh a hl in th psitiv plat and cllids with th ngativ plat at a spd f.0 x 0 m/s. What is th ptntial diffrnc btwn th plats? (6.8 x 0 - ) nrgy is cnsrvd as sm f th kintic nrgy is cnvrtd t lctrical ptntial nrgy Σ = Σ = + k k l mv mv = + = = m(v - v ) - (9. x 0 )[(.0 x0 ) - (.0 x0 ) ] = (. 60 x 0 ) 4 If th lctric fild btwn th plats is.70 x 0 /m, what is th spd f th alpha particl whn it rachs th ngativ plat? (8. x 0 4 m/s) Wrksht 9: Millikan s Oil Drp xprimnt ) An il drp wighs.84 x 0 -. If it is suspndd btwn tw hrizntal paralll plats whr th lctric fild strngth is.0 x 0 4 /, what is th magnitud f th charg n th il drp? (.0 x 0-9 ) S tr Dam Pag

22 If th il drplt is hld statinary, thn th upward lctric frc must balanc with th dwnward gravitatinal frc. If th il drplt is hld statinary, thn th upward lctric frc must balanc with th dwnward gravitatinal frc. = g mg mg.84 x 0 4. x 0.0 x 0 9 = g mg = mg d mgd x 0 (9.8)(0.06).9 x x x 0 x.6 x ) An il drp with a mass f 4.80 x 0-6 kg is suspndd btwn tw hrizntal paralll plats that ar 6.00 cm apart. If th ptntial diffrnc btwn th plats is.90 x 0, hw many xcss lctrns ds th il drp carry? () x 0 ) An il drp with a mass f 7.0 x 0-6 kg is mving up at a cnstant spd f.0 m/s btwn tw hrizntal paralll plats n th insid f an vacuatd irn pt lik Millikan s. If th lctric fild strngth is.0 x 0 4 /m, what is th magnitud f th charg n th il drp? (. x 0-9 ) If th il drplt is mving upward at a cnstant vlcity, thn th upward lctric frc must balanc with th dwnward gravitatinal frc. S tr Dam Pag

23 = g mg mg 6 7. x 0 (9.8) 4.0 x 0 9. x 0 4) An il drp whs mass is.0 x 0 - kg acclrats dwnward at a rat f.0 m/s whn placd btwn tw hrizntal paralll plats that ar.00 cm apart. Assuming th il drp is ngativ and th tp plat psitiv, hw many xcss lctrns ds th il drp carry if th ptntial diffrnc btwn th plats is.8 x 0? () If th il drplt is acclrating dwnward vlcity, thn th upward lctric frc must b lss than th dwnward gravitatinal frc. = - + nt g ma = - + mg md(a - g) -. x 0 (0.0)( ) -.8 x x x 0 x.6 x ) During a Millikan il drp xprimnt, a studnt rcrds th wight f fiv diffrnt il drps. A rcrd is als mad f th Ptntial Diffrnc ncssary t hld ach drp statinary btwn tw hrizntal paralll plats. (slp = /4 x 0 4 ) Mass (0-6 kg) Ptntial Diffrnc (0 ) a) Draw a graph shwing vltag as a functin f wight. b) What ds th slp f th graph rprsnt? c) If th distanc btwn th plats was a cnstant 0.40 m, what is implid abut th charg n ach f th drps? (.6 x 0-8 ) L = Mass (0-6 kg) L = ltag () L = Wight f g () L Wight () Manipulatd = Wight () 8.6 x 0-8 spnding = ltag () 6. x 0-8 ntrl = distanc btwn plats 4.4 x x 0-8. x 0-8 Ling(ax+b) L, L, Y a =.4 x 0 7 / b = r = min max scl Windw x[.9 x x 0-6 x 0 - ] y[ ] In a balancd situatin lik this, th upward frcs will b ual t th dwnward frcs. S tr Dam Pag

24 If th il drplt is statinary, thn th upward lctric frc must ual th dwnward gravitatinal frc. = g g = g d d g = Sinc slp = / using th uatin abv d d slp = and hnc slp x x 0 9 g 7) In a Millikan il drp xprimnt a studnt sprayd il drplts with a dnsity f 7.8 x 0 kg/m btwn tw hrizntal paralll plats that wr 4.0 cm apart. Th studnt adjustd th ptntial diffrnc btwn th plats t 4.6 x 0 s that n f th drps bcam statinary. Th diamtr f this drp was masurd t b.4 x 0-6 m. What was th magnitud f th charg n this il drp? ( sphr = 4/πr ) (4.8 x 0-9 ) If th il drplt is statinary, thn th upward lctric frc must ual than th dwnward gravitatinal frc. = g g = mg d mgd = 6) An il drp whs mass is.70 x 0-6 kg acclrats upward at a rat f.90 m/s whn placd btwn tw hrizntal paralll plats that ar.0 cm apart. If th ptntial diffrnc btwn th plats is 7.9 x 0, what is th magnitud f th charg n th il drp? (.0 x 0-9 ) If th il drplt is acclrating upward, thn th upward lctric frc must b gratr than th dwnward gravitatinal frc. 4 ρ π = ( r )gd 4 π 6 7.8x0 ( [. x 0 ] )9.8(0.040) x x 0 = + - nt g ma = + -mg ma = + -mg d md(a + g) 6.7 x 0 (0.0)(.9-9.8).9 x 0.0 x 0 9 8) An il drplt ( -) is suspndd btwn tw paralll chargd plats ( = 7 ). If an il drplt f th sam mass but a charg f - t b suspndd btwn th sam plats, what ptntial diffrnc wuld b ncssary (9 ) If th il drplt is statinary, thn th upward lctric frc must ual than th dwnward gravitatinal frc. S tr Dam Pag 4

25 = g g = mg d mgd = mgd nw = = mgd ld = nw ld = (7) nw nw = 9 9) In an il drp xprimnt similar t Millikan's, an il drplt is suspndd btwn tw paralll chargd plats. alculat th magnitud f th charg n th il drplt givn th fllwing: radius f th il drp 4. x 0-6 m dnsity f th il 7.8 x 0 kg/m distanc btwn plats.0 cm ptntial diffrnc btwn plats 99 (4.80 x 0-6 ) If th il drplt is statinary, thn th upward lctric frc must ual than th dwnward gravitatinal frc. = g g ρgd = 4 r ρ π gd 4 π x 0 ( [4. x 0 ] )9.8(0.00) x ) In Millikan's il drp xprimnt an il drp having a mass f 6.00 x 0-7 kg is acclrating upward at a rat f 4.60 m/s whn sprayd btwn tw hrizntal paralll plats.00 cm apart. If th ptntial diffrnc btwn th plats is 9.00 x 0, what is th charg n th il drp? (4.80 x 0-9 ) If th il drplt is acclrating upward, thn th upward lctric frc must b gratr than th dwnward gravitatinal frc. = + - nt g ma = + -mg ma = + -mg d md(a + g) x 0 (0.00)( ) x 0 9 = mg d Wrksht 0: lctric urrnt S tr Dam Pag

26 ) A currnt f.60 A flws fr. s thrugh a cnductr. alculat th numbr f lctrns that pass thrugh a pint in th cnductr in this tim. (.44 x 0 0 ) Q = I t Q = (.60)(.) Q =.08 x.6 x Q =.44 x 0 ) Hw lng wuld it tak.0 x 0 0 lctrns t pass thrugh a pint in a cnductr if th currnt was 0.0 A? (. s) Q t = I t = 0 t =. s ) alculat th currnt thrugh a cnductr, if a charg f.60 passs thrugh a pint in th cnductr in.4 s. (.64 x 0 - A) Q I = t.6 I =.4 I = 0.64 A 4) If.6 x 0 0 alpha particls pass a pint in spac vry 0.0 s, what is th currnt at this lcatin? (6.8 A) Q I = t 68. I = 0 I = 6.8 A ) If 4.0 x 0 - A f lctrn currnt passs btwn th trminals f a.0 battry in.0 s, hw much nrgy has th battry usd up in this tim? (6. x 0 - J) = whr Q = It givs = It =.(4 x 0 )(.) = 6. x 0 J 6) If a currnt f.0 A passs thrugh an lctric circuit fr 4.00 s, hw many lctrns hav passd any givn pint in th circuit? (8.00 x 0 9 ) Q = I t Q = (.)(4) Q =.8 x.6 x Q = 8.00 x 0 7) Thr ar 7.0 x 0 7 prtns travling thrugh a rgin f spac vry hur. What is th lctric currnt at this pint? (. x 0 A) x x 0 p x =.0 x 0 + p Q I = t.0 x 0 I =.6 x 0 I =. x 0 A 9 S tr Dam Pag 6

27 8) Whn an lctric applianc is cnnctd t a.0 x 0 pwr lin, thr is a currnt thrugh th applianc f 8. A. What is th avrag amunt f nrgy givn t ach lctrn pr scnd by th pwr lin? (.9 x 0-7 J/s) = whr Q = It givs = It = 0(8.)() =.96 x 0 J 8. x.60 x 0 9 =.47 x x 0 =.47 x 0 = J 7.9 x 0-0 S tr Dam Pag 7