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Transcript
TIPERs D3-SCT03: Two M A G N E T S — F O R C E Three students are discussing the strengths (or magnitudes) of the forces between two permanent magnets. The smaller magnet is moving to the right. The larger magnet is stronger than the smaller magnet. v = 0 Alejandro: "The velocities and magnet strengths don 7 matter. Themagnets will attract each other with equal strength." ^ Bernardo: "No, the stronger magnet will push more than the weaker one because it has a stronger field. " Cecilia: "/ don't think we can compare the strength of the forces unless we know the velocity of the smaller magnet." With which oTthese students do you agree? Alejandro r Bernardo Explain your reasoning, ri- 'P'^ Cit/^'/ -f '"J Cecilia /^j^r^^^^^ /^^ Held None of them ^^y^^^j^j^^ ir^^-^r^ CinameC a^^J pur fd •\/ ffWilC^ J^J ^/ b3-SCT04: ELECTRIC C H A R G E NEAR A B A R M A G N E T — F O R C E DIRECTION Consider the following students' statements about the magnetic force on a positively charged particle placed at rest near a permanent magnet. I Aurelia: "A positively charged particle placed near the north pole of a permanent magnet will experience a repulsive force because the north pole acts like a positive charge. " Ben: "/ think it will experience an attractive force, but not because it is a magnet. " Chila: "Since it's not moving, I think it won't experience any electromagnetic force." With which of these students do you agree? ': Aurelia Ben Chila K None of them Explain your reasoning. Copyright © 2 0 1 5 Pearson Education, Inc. 344 /f^ TIPERs D 3 - R T 0 7 : M O V I N G C H A R G E P A T H — D I R E C T I O N AND STRENGTH OF T H E MAGNETIC FIELD In each case, the shaded region contains a uniform magnetic field that may point either into the page or out of the page. A charged particle moves through .the region along the path indicated. A l l of the charged particles have the same mass and enter the region with the same initial speed. B - C ) ' U'-'i lit!'' J I u - +g 1 ( ^ 1 Rank the magnetic field in the region. Fields directed out of the page (considered positive) are ranked higher than fields directed into the page (considered negative). R 1 1 Greatest /' 2 Explain your reasoning. ' \ \ 3 J r iJ^s^- OR t 'D 5 4 6 Least a. All All the same • zero Cannot determine D 3 - R T 0 8 : CHARGED-PARTICLE A N D A UNIFORM MAGNETIC " F I E L D — F O R C E In each case, a charged particle is moving in a uniform magnetic field. The particle charge and the strength of the field vary among the four cases. The particles all have the same mass, and they were all given the same imtial speed. B ? = +9 nC 9 = +5 nC (? = +15nC r = 1 cm r = 2 cm r = 3 cm Rank the magnitude of the force on each charge. ,1 Greatest I 2 II 3 II OR 4 Least All the same Cannot determine All zero Explain your reasoning. ^ . ^ ^ ^ . ^ / ^ ^ ^ ^ ^ ^ f ^n^^ There r ^ ^ - i ^ , / ^ ^ / ^ ~ 2015 Pearson Education, Inc. 346 / r t- TIPERs D 3 - L M C T 1 0 : M O V I N G C H A R G E WITHIN A UNIFORM M A G N E T I C F I E L D — F O R C E A positively charged particle moving at a constant speed is entering a region in which there is a uniform magnetic field. The particle follows the curved path shown. +1 A number of changes to this imtial situation are described in (a)-(f) below. Select from choices (i)-(vi) how each change will affect the magnetic force on the particle shortly after it enters the magnetic field. This change will: (i) alter only the direction of the force on the particle. (ii) only increase the magnitude of the magnetic force on the particle. (iii) only decrease the magnitude of the magnetic force on the particle. (iv) alter both the magnitude and direction of the magnetic force on the particle. (v) not affect the magnetic force on the particle. (vi) cause the magnetic force on the particle to be zero. -(f ' 0 ^ ' '' Each change below refers to the initial situation described above: (a) The +q particle is replaced by a +2q particle. Explain your reasoning. r P*'/ ,, // r , f (b) The +iy particle is replaced by a » q particle. V qyr a/ - - ^ x p l a i n your reasoning. / / • ^,r,^- ,c , / ^ \/ cM'-.;e J>U. / k^'-fp ^k-e /o (c) The +9 particle is replaced by a neutral particle. 1^/ Explain your reasoning. ^ / ^ r- • t^'J' f ''Of^?Ce *^<>L?/^^'rr /^S/^ (d) The particle enters the region moving at a slower initial velocity. • / Explain your reasoning. ^. - . tv^'fi //.^ (e) The magnetic field is one-third its original strength, f ' / ^Explain your reasoning. / / ' ' . • / , . • - ; , r / y ' y / 7^/* (f) The direction of the magnetic field is parallel to the particle's initial velocity. Explain your reasoning. 1 / - ,v / . ' .^.n.,... Copyright © 2 0 1 5 Pearson Education, Inc. r ......^ ^, ...... ' k-.^, r::.'.r i^.^j </f , hit/' TIPERs D3-RT13: C U R R E N T - C A R R Y I N G W I R E IN A UNIFORM M A G N E T I C F I E L D — M A G N E T I C FORCE The figures below show identical current-carrying wire segments in identical uniform magnetic field regions. A l l the magnetic field regions are the same width and height. B D ® (g>i (g B ® ® ® (gi ® (gl (g (g Rank the strength (magnitude) of the magnetic force on the wire segments. 1 I 2 II y/ OR 3 4 Least Greatest All the same Explain your reasoning. / AU zero -7~ Cannot determine / X) D /• l/lJ D3-TT14: P A T H OF A M O V I N G ELECTRON I N A UNIFORM MAGNETIC FIELD An electron is moving to the right at a velocity v when it enters a region containing a uniform magnetic field pointing into the paper. The path of the electron in the magnetic field is shown. \ ® ®~® ®~® ® ®l ®'.®I <8i ® ® %jk % ®| I® ® ® ® ® ®^^<8i ® ®| I® V 10 (g, ^ j g ^ ^ r ® ® ® ® ®i There is at least one error in the diagram. Identify all errors and explain how to correct them. {Urvim C^U/ur/ cToCk'- i^rcr. / ' / ^>.o{^,;V 'J r Copyright © 2 0 1 5 Pearson Education, inc. 350 'Oi''k:o'/r-y^ fff/'i^C TIPERs D 3 - L M C T 1 6 : C U R R E N T IN A UNIFORM MAGNETIC F I E L D — M A G N E T I C FORCE A section of straight wire within a magnetic field is conducting a current to the right. The external magnetic field is uniform and directed into the paper. ® ®g I® ® ® / ® ® ® ®l ; ® ® ® ® ^ ® ® ® ® ® j L®-®. ®-'^. ^-l^J A number of changes to the initial force are described m (a)-(e) below. Select from choices (i)-(vii) the possible causes of the change in the force. This change could be caused by: (i) (ii) increasing the current. decreasing (but not to zero) the current. (iii) (iv) reversing the direction of current. increasing the strength of the magnetic field. (v) (vi) (vii) decreasing (but not to zero) the strength of the magnetic field. reversing the direction of the magnetic field. none of these. If more than one choice is correct, please indicate all correct choices for the answer. Each change below refers to the initial situation described above: (a) The magnetic force on the wire is larger and in the same direction, r . / l.."^ Explain your reasoning. ,^ ' j r^y)'Jr'A inUtacf tarymt kaj/in^^'^Tvwarie^cC ff£('^ <<xin. (c) The magnetic force on the wire is smaller and in the same direction. • Explain your reasoning. ^ "> ^l^-n^r ^^cfty^r /LJrr'€rr' dd'^/'^J'^r C, / ^ / ( '•/ 9 ' / i —' ' ' ^ / j (b) The magnetic force on the wire is larger and in the opposite direction. L ^ ( Explain your reasoning. ^ x :v^r^' ^. ./ rfefc< o-r h''^-'. (d) The magnetic force magnitude remains the same, but the direction changes. / / / Explain your reasoning. J ' . ' (e) The magnetic force on the wire is zero. Explain your reasoning. f I r-'h.y r C ^'^ ^ ^ i ^[ f , Copyright © 2 0 1 5 Pearson Education, Inc. • , . r \/' ffw^ D 3 MAGNETISM D 3 - Q R T 1 7 : STRAIGHT C U R R E N T - C A R R Y I N G W I R E — M A G N E T I C FIELD N E A R B Y The figure below shows a point P near a long current-carrying wire. f'C (lofy'A ^JM^'j tjen i^'^, "TA^ (a) What is the direction of the magnetic field at point P due to the current in the wire? I Explain your reasoning. oaf ff'^^ comiAq j / / -hward Of •/^-^ f^Ciji^r utu. Hfni tAour /^^'AT' -fiiuit?^ (b) WTiat would the direction of the magnetic field at point /" be if the current in the w i r e j w ^ reversed? Explain your reasoning. \ //I fM&uicJ i . cMwmUf tm ^ / of df/^Utiyi / Hc(^. f-f *' / e^ooufj, lA-lv -HAE paper -Hr^re, \ ' ' -• (c) What would happen to the magnetic field at point P if the current in the wire werelncreased? Explain your reasoning. /-h MCcHd rf^-f lacl^cry'iJHm s/rcy^C S'^'r<^^-^er f'k curywi-f- /y\d^yteHr fe/^^ ci^^ m-ennr 7}t€se /i^^e fie/Wr ^Jd mcuMj C^P ' (d) What would happen to the magnetic field at P if point P were farther away from the wire? Explain your reasoning. / . / -r? . ,^ . • •• iP y-y^ f*^ D 3 - W W T 1 8 : C U R R E N T - C A R R Y I N G W I R E — M A G N E T I C FIELD DIRECTION A long, straight wire is conducting a current whose direction is pointed out of the paper toward you. A student makes the following statement: / ^ "The magnetic field generated by this wire points straight out from the wire." l/\J ^ What, if anything, is wrong with this statement? If something is wrong, explain the error and how to correct it. If the statement is valid, explain why. '/^^ lii.e Chryi:je rin'^J pok^ I hnauu iUtr€ ycf J ekcrric frffj IS ri6 ihr^ucfh ^hf'c^ h^mrMj Copyright © 2 0 1 5 Pearson Education, Inc. j ^ 353 W U<-f Cf'-aycji h -^-^— f^^ ^f'fU L-urrent-canying wires are positioned at the comers or a square. A l l of the currents have the same magnitude, put some are into the page and some are out of the page. B -^^.-aS ®—fl—0? 1 Rank the magnitude of the net magnetic fidd'atthe center of the square. OR 1 Greatest AU the same ;ast All zero Cannot determine Explain your reasoning. difkkl Wdwr ^ rtiinf-kml ^^-^^ fir fao- curwnHi^if/ sko^^. ht^f^e bu, tifk-rr "^dd €>/ r^Mc^f aaik cdk'sy -ut~, A? A-f 0 eaik fi-efj ^/h\/-^-e ^kP^C're rarn-rr^. I r\ Csmoef, b.^- U-^ h^A-t-r yfr upper rrfkrP A I R S OF LONGI CURRENT-CARRYING W I R E S — M A G N E T I C FIELD N E A R B Y ^ / , ' ^^^^y, IS C<ikM(i&d bcjAmfker' f^pp^ f^fj ^^p^jJ^m^r rtfhf D3-RT25: dj/. ^ ^ ., In these cases, the two parallel wires have the same magnimde current perpendicular to the plane of the page. The direction of the current in each wire is shown. A B c r P e r C c r > r 0 c, r P 1r < if > 9 v.r Rank ti^^agnituj^e of the magnetic field at pomt P. OR 1 4 Least Greatest Explain your reasoning. \ r J,.,^frd^ diskrcf All the same All zero Cannot determine 4 ik€ /:&Jcifff j>r^^'^--^^ ^ Copyright © 2 0 1 5 Pearson Education, Inc. 357 • u D 3 MAGNETISM D 3 - T T 2 7 : MOVING A W A Y POSITIVE C H A R G E NEAR STRAIGHT C U R R E N T - C A R R Y I N G W I R E — F O R C E At the mstant shown, a positively charged particle has a velocity that is perpendicular to a current-carrying wire. ^^•^ ike kfrH-f- (fd^ ( b i i w e t n us / fk-e cck^i J &fk/( A sfaident makes the following statement: "The force exerted on the charged particle by the magnetic field is zero because the velocity is parallel to the magnetic field produced by the wire." There is at least one problem vdth this student's contention. Identify any problems and explain how to correct fl.^J'Zo... ^ f ^^^^^ d'r^Mj ry-rkfl,e ^^-^-^ h D 3 - R T 2 8 : M O V I N G C H A R G E A L O N G A STRAIGHT C U R R E N T - C A R R Y I N G W I R E — A C C E L E R A T I O N Four charged particles have been projected parallel to identical current-carrying wires. The particles have the same mass and are projected with the same initial speed. ^ = -1-5 nC • • B ^ = -i-10nC ^ 4 cm +5 nC 4 cm ^ = H-10nC T • 2 cm t 2 cm Rank th^ magnitude of the acceleration of each charge at the instant shown p t 1 Greatest 2 1 A 6 3 4 Least OR All the same All zero Cannot determine Explain your reasoning. kf ^ ^ urn cat ^ 'fie(d f^^^^kfh iv ijk^l kf^ i ^ / k^Mmck-fnnff^ 'kJoatl^ J J Copyright © 2015 Pearson Education, Inc. 359 iMm M^Z tIPERs D 3 - Q R T 2 9 : MOVING C H A R G E NEAR A STRAIGHT C U R R E N T - C A R R Y I N G W I R E — A C C E L E R A T I O N At the instant shown, a particle with charge of +7 nC is moving at 3 m/s parallel to a long, straight wire that has a current of 8 A. itm I - , V = 3 m/s ^ . •> / X / q = +laC Ckc'mi < / ,c < d(€ h jM k(d, /f/S . fi^y. WffC ^ - - r r ' C ^ ) , (a) What is the direction of acceleration of the charged particle? Explain your reasoning. l/yl(t . /, / hcAjcyi^ ^ aa.fkrUHnCi (Ap 'hf.'J^Uci ipy hp ^( -Jk-P ppi>^' ^ c/n it. (mJfy^ h^^^^r poCnfr uJri/n^^o i^f UrQ.^ix. forre ackr^ n^tciJk poi>h ink R^M Mik< 8 fiefd, pf< fhukfto . ^^^'^ (b) If we double the charge on the particle, what will happen to the acceleration? Explain your reasoning. / / in ^ / / / pp:u -o d^typi^ ^ - fUB^^rk ^^'f^'ir-^j /" / 5 p (c) If we replace the charge with la negative charge of the same mass and same magnitude charge as the original charge, what will happen to the acceleration? Explain your reasoning. / / ^<y/V/ k ^p^O^f^ dir^im ak fkf fdi^€' ra.k. (d) If we double the distance from the wire to the particle, what will happen to the acceleration? Explain your reasoning. / / /^//f fO /^^ n^(mX€ 1" ^ yfa, (e) If we double the mass 5s of of the the particle, particle, what what will will happen happen to to the the acceleration? a c c e l e r d^i'^fr^j 5^ a t i o n ri'iru ^ Explain your reasoning. -'• - I — (f) If we double the velocity of the particle, what will happen to the acceleration? Explain your reasoning. (g) If we reduce the magnitude of the current, what will happen to the acceleration? Explain your reasoning, p .^p,) idpi redco;.: 0i^PaMC£ prop ? ("- y/.. /'•fiduyfrq iy-^ C^rr (h) K we reverse the direction of the current, what will happen to the acceleration? Explain your reasoning, •jiff ^ ' J ^pppP^J^ £a^'^ ir. PpP^^^^ kP<^k^' ^^rii^' Copyright © 2 0 1 5 Pearson Education, Inc. 360 d irtci^m- ^iYii