reviewer for the second quarterly test in science 4a

8/13/2019 Reviewer for the Second Quarterly Test in Science 4a

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Magnetic Force on an Electric Charge Moving

in a Magnetic Field

Magnitude:F = qvB sin WhereF = magnetic force, Newton (N)q = charge , Couom! (C)

v = veocit", meter #er second (m$s)B = magnetic fied, %esa (%) = ange !et& veocit" and fied (')

irections:ight hand rue (*)

Where:%hum! + magnetic forceointee + magnetic fiedMidde finger + veocit"

%his convention is on" true for the#ositive charge& -f it the charge is negative,ta.e the o##osite direction that "ou wi getfrom the *&/am#e ro!em:0& 0 #roton having a s#eed of 1&23425m$s in amagnetic fied fees a force of 6&2342748 Ntoward the west when it moves vertica"u#ward& When moving in norther" direction, itfees 9ero force& What is the magnitude and

direction of the magnetic fied in this region(%he charge of a #roton is ;4&534274& 73& ;9/outions:4& v=&23425m$s, ;" B=2&1%,;" =2'q=;4&534274


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-ts /- unit is Couom! (C)&@ectron

-t is the smaest and ightest of the#artices in an atom&

-t is in constant motion as the" circearound the nuceus of that atom&

-t has a negative charge, which meansthat the" seem to !e surrounded !" a.ind of invisi!e force fied& %his is caedan electrostatic field.

roton

-t ismuch arger and heavier thaneectron&

-t has a #ositive eectrica charge&

-ts #ositive" charged eectrostatic fiedis e3act" the same strength as theeectrostatic fied in an eectron, !ut it iso##osite in #oarit"& -n other words, the#roton is e3act" as #ositive as theeectron is negative&When certain t"#es of materias are

ru!!ed against other certain t"#es, chargema" !e transferred from one to the other&

@ach o!Aect contains charge& For mosto!Aects, the num!er of negative charges equasthe num!er of #ositive charges, giving a netcharge of 9ero& %hese charges are free to move,however

When certain t"#es of materias areru!!ed against each other, the materias atomsare arranged such that some of the chargesfrom one materia wi !e transferred to theother materia& %his gives !oth o!Aects a netcharge& ne o!Aect wi !e #ositive" charged,the other wi !e negative" charged&

When an uncharged o!Aect is #aced neara charged o!Aect its charges rearrangethemseves& %hose charges attracted tothe charged o!Aect move towards thecharged o!Aect and those chargesre#eed move awa"& %his effect is .nownas #oari9ation&

Dravit" and @ectric Force@ectric force is stronger than gravit"&eca that a o!Aects e3ert an attractive

force on each other according to Eaw ofniversa Dravitation (ED)

Gui9 + Fi in the !an.s& Write theanswer on "our ut#uts Note!oo.

4& %wo uni.e eectric charges HHHHH eachother&

>& Com#aring eectric and gravitationa

forces, it wi !e found that HHHHHHHHHis wea.er&

& When "ou com! "our hair, hair !ecomes#ositive !ecause HHHHHHHHHH have !eentransferred from it to com!&

8& %he charge on the com! is designated asHHHHHHHHHH&

1& Metas are said to !e good HHHHHHHH!ecause eectric charges move free"through them&

5& u!!ing is a wa" of charging an HHHHHHH&?& H HHHHHHHHH is a wa" of charging a

conductor without contact&6& HHHHHHHHHHH is a device used to stud"

charges and their interactions&& Dravit"& @ectrons8& ositive" charge1& Conductors5& -nsuators?& -nduction6& @ectrosco#e


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Coulombs Law

Couom!s aw7-t descri!es the force !etween two charged#artices&7-t states that the eectrostatic force isdirect" #ro#ortiona to the #roduct of the

amount of charges and inverse" #ro#ortiona tothe square of their se#aration distanceF = .q4q>$r

>whereF = eectrostatic force,. = (Couom!s constant)q4= first charge,q>= second charge,and r = the distance !etween the two charges&What ha##ens to the eectrostatic force when

the HHHHHHHHH7#roduct of the charges is dou!ed

-t wi !e dou!ed7se#aration distance is dou!ed

-t wi !e reduced to J7se#aration distance is reduced to K

-t wi !e quadru#ed&7#roduct of the charges is dou!ed andse#aration distance is reduced to K

-t wi !e eight times as much

7#roduct of the charges is dou!ed andse#aration distance is dou!ed

-t wi !e reduced to K/am#e ro!emWhat is the eectric force the two charges of;43427?C and 7434275C se#arated !" 43427mdistanceq4 = ;43427?C, q> = 7434275C, r = 43427m. =

F = .q4q>$r>

F = (;43427? C) 7434275 C(43427m)>

F = 7 )&

*ow then can we ta. a!out forces if weon" have one charge

%he soution to this diemma is tointroduce a test charge&

We then determine the force that woud!e e3erted on it if we #aced it at acertain ocation&

-f we do this for ever" #oint surroundinga charge we .now what woud ha##en ifwe #ut a test charge at an" ocation&

%his ma#s of what woud ha##en at an"#oint we ca a fied ma#& -t is a ma# of

the eectric fied due to a charge& -t tesus how arge the force on a test chargewoud !e and in what direction the forcewoud !e&

ur ma# consists of the ines that te ushow the test charge woud move if itwere #aced there&

Test Charge

%his is the .e" to ma##ing out an eectricfied& %he equation for the force !etween

two eectric charges has !een shownearier and is:F = .q4q>$r

>

-f we want to ma# the fied for G4thenwe need to .now e3act" what woud ha##en if we#ut G>at ever" #oint around G4& But thiso!vious" de#ends on the vaue of G>& %his is atime when we need to agree on a convention&What shoud G>!e when we ma.e the ma# B"

convention we choose G>= ; 4C& %his means that if we want to wor. out

the effects on an" other charge we on"have to muti#" the resut for the testcharge !" the magnitude of the newcharge&

%he eectric fied strength is then Austthe force #er unit of charge and has thesame magnitude and direction as the


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force on our test charge !ut hasdifferent units:

%he eectric fied is the force #er unit ofcharge and hence has units of newtons#er couom! LN$C&

/o to get the force the eectric fiede3erts we use:

F = G@What do field maps look like

ositive Charge 0cting on a %est Charge

We can see that at ever" #oint the #ositivetest charge, q, woud e3#erience a force #ushingit awa" from the charge, G& %his is !ecause !othcharges are #ositive and so the" re#e& 0sonotice that at #oints further awa" the vectorsare shorter& %hat is !ecause the force is smaerif "ou are further awa"&!egative Charge "cting on a Test Charge

Electric Field of !egative and #ositive Charge

in $solation

Two Like Charges $% The #ositive CaseWhat about the &trength of the Electric

Field

0s "ou move further awa" from thecharge the fied ines !ecome more s#read out&-n fied ma# diagrams the coser fied ines aretogether the stronger the fied&0& -dentif" the t"#e of charge on o!Aects 07!ased on the eectric fied ines shown for eachconfiguration of charges&

a& #ositive !& negative c& neutra

4&&

>&

B& Construct eectric fied ines around the

foowing configuration of charges& -ncude ateast si3 ines #er charge&8

1&

C& Fi in the !an.s5& 0t a ocation of 2&>22 m from o!Aect 0, theeectric fied strength is 2&2122 N$C& -f theeectric fied strength were measured at a

an


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ocation of 2&82 m from o!Aect 0, then the fiedstrength woud !e HHHHHHH N$C&?& 0t a ocation of 2&>22 m from o!Aect 0, theeectric fied strength is 2&2122 N$C& -f theeectric fied strength were measured at aocation of 4&222 m from o!Aect 0, then thefied strength woud !e HHHHHHH N$C

6& 0t a ocation of 2&>22 m from o!Aect 0, theeectric fied strength is 2&2122 N$C& -f theeectric fied strength were measured using atest charge with twice the charge at a ocationof 2&>22 m from o!Aect 0, then the fiedstrength woud !e HHHHHHH N$C22 m from o!Aect 0, theeectric fied strength is 2&2122 N$C& -f theeectric fied strength were measured using atest charge with twice the charge at a ocation

of 2&422 m from o!Aect 0, then the fiedstrength woud !e HHHHHHH N$C&5& 0t a ocation of 2&>22 m from o!Aect 0, theeectric fied strength is 2&2122 N$C& -f theeectric fied strength were measured at aocation of 2&82 m from o!Aect 0, then the fiedstrength woud !e '.'()* !+C&?& 0t a ocation of 2&>22 m from o!Aect 0, theeectric fied strength is 2&2122 N$C& -f theeectric fied strength were measured at a

ocation of 4&222 m from o!Aect 0, then thefied strength woud !e '.'')'' !+C6& 0t a ocation of 2&>22 m from o!Aect 0, theeectric fied strength is 2&2122 N$C& -f theeectric fied strength were measured using atest charge with twice the charge at a ocationof 2&>22 m from o!Aect 0, then the fiedstrength woud !e '.'*'' !+C22 m from o!Aect 0, theeectric fied strength is 2&2122 N$C& -f the

eectric fied strength were measured using atest charge with twice the charge at a ocationof 2&422 m from o!Aect 0, then the fiedstrength woud !e '.)'' !+C&Electricit,

Charges in Motion

@ectric Fied, Wor. and @ectricotentia

Wor. is done !" gravit" in first figure&%he #otentia energ" decreases as .inetic energ"increases

Wor. is done !" an e3terna force in secondfigure& %he #otentia energ" increases as .inetic

energ" decreases

@ectric Fied, Wor. and @ectric otentia

Electric #otential in Circuits


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Charge moving through the wires of the circuitwi encounter changes in eectric #otentia as ittraverses the circuit& Within theeectrochemica ces of the !atter", there is aneectric fied esta!ished !etween the twoterminas, directed from the #ositive termina

towards the negative termina& ositive termina of the !atter"

0s the charge move through the cesfrom the negative termina to the #ositivetermina woud require wor., thus increasing the#otentia energ" of ever" Couom! of chargethat moves aong this #ath& %his corres#onds toa movement of #ositive charge against theeectric fied& -t is for this reason that the#ositive termina is descri!ed as the high

#otentia termina& Negative termina of the !atter"

%he charge woud ose #otentia energ" asmoves through the e3terna circuit from the#ositive termina to the negative termina& %henegative termina is descri!ed as the lowpotential terminal

@3ercise& Which of the foowingstatements are true a!out an eectriccircuit ut chec. mar. on a that a##"&

4& @ectrons are the mo!ie charge carriersin an eectric circuit&

>& %he #ath of charge fow from the ; tothe 7 termina of the circuit can consistof nonconductive materia&

& -n an eectric circuit of an automo!ie,the 4>7ot car !atter" is sometimesreferred to as the interna circuit!ecause it is ocated inside of the hoodof the car&

8& Charge is su##ied with energ" in theinterna circuit and the energ" istransformed into other forms in thee3terna circuit&

1& Charge is consumed as it moves throughthe energ"7transforming devices of thee3terna circuit& For instance, the amountof charge entering a ight !u! in a second

is ess than that which e3its the ight!u! in a second&

5& 0 !atter" is used to #ower a fashightcircuit& When the !atter" no ongerwor.s, it is !ecause it has run out ofcharge&

?& %he ocation on an eectric circuit where

the charge #ossesses the greatestamount of eectric #otentia energ" is the; termina of the !atter"&

0 are a##ica!e&4& @ectrons are the mo!ie charge carriers in aneectric circuit&>& %he #ath of charge fow from the ; to the 7termina of the circuit can consist ofnonconductive materia&& -n an eectric circuit of an automo!ie, the 4>7

ot car !atter" is sometimes referred to as theinterna circuit !ecause it is ocated inside ofthe hood of the car&8& Charge is su##ied with energ" in the internacircuit and the energ" is transformed into otherforms in the e3terna circuit&1& Charge is consumed as it moves through theenerg"7transforming devices of the e3ternacircuit& For instance, the amount of chargeentering a ight !u! in a second is ess than that

which e3its the ight !u! in a second&5& 0 !atter" is used to #ower a fashight circuitWhen the !atter" no onger wor.s, it is !ecauseit has run out of charge&?& %he ocation on an eectric circuit where thecharge #ossesses the greatest amount ofeectric #otentia energ" is the ; termina of the!atter"&-hms Law

-t states that at constant votage, the

eectric current increases when the resistancedecreases&hmOs Eaw- = $ = - = $-Where

- = eectric current (am#ere, 0) = votage (vot, )


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= resistance (ohm,P)/am#e ro!ems:

4& 0 !ender with a resistance of >12P is#ugged in a >>27 outet& *ow muchcurrent wi fow through it

>& 0n eectric fan is #ugged in a >>27outet& *ow much resistance does it have

when a current of 2&0 fows through it& 0 !atter" is #aced in 81P % remote

contro and a current of 2&>0 fowsthrough it& What is the #otentiadifference offered !" a !atter"

4& = >12P =>>2- = $- = >>2$>12P- = 2&660

>& =>>2 -=2&0

= $- = >>2$2&0 = ?& P

& = 81P -=2&>0 = - = 2&>0(81P) = ;;n 4$%=4$4;4$>;4$;4$n

Current ineach oad

/ame in a oads-%=-4=->=-=-n

aries in each oadde#ending on theresistance of theoad

-%=-4;->;-;-n

otage ineach oad

aries in each oadde#ending on theresistance of theoad%=4;>;;n

/ame in a oads%=4=>==n

/am#e ro!em

4& %hree am#s with resistances of P, 8P and1P are connected in series with =8P=1P%=;4$;4$n

4$%=4$P ;4$8P ;4$1P4$%=8?$52%=52$8?%=4&>6 P%=4=>==;--4=4$4-4==>$>

->==>&>10-=$-=;%=>&>1;;&?1%=P)%=;--%=0;>&>10;4&60-%=?&210-%=%$%-4=?5P-4=?&210

reviewer for the second quarterly test in science 4a

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