Chapter 22-23 Review Name ANT ~Il Z.

1. a. Where do the electrons come from that produc heat and light in a bulb? -f/&lt1b. Does voltage flow through a circuit, or is voltag established acro circuit? C~OtuTI<C..f;

c.t!.t/AU~AAJ!)AkJ""lJc. What is Ohm's Law? 12. ::' ~

.rd. Why are thick wires rather than thin wires used to carry large currents?

__ -r._ok_I_L_k._w_' ~_~_•.J_tl_t! VI!' L e <.5 a.CoSl.$'li AU e:. J (!L.tJ ()oS(. L 1!:s..5 f'0 ().J~I!

•

2. a. What has a greater resistance, a~o-watj»r a lSO-watt bulb?

P.;- I V::,f Clr Ij IUhllJlfJ~ {O~0 IF P11<,b. If three lamps of equal resistance are connected in parallel to a 6-voit battery, how manyvolts are across each lamp? PALALL! L fYt,!JfAl.5. .$.fttI1.f VOLT~Yft : 6 Vc. Why does the Wtal circuit Tistanre decreas1 when resistors are added in parallel?

K.t 1Zt.t.~ '1; tit it ...d. Calculate the current in a l40:W electntblanRet connected to a 120-Voutlet.

P=14l)1U 1/::: 120v I = ~P=I V

3 a. What is a short circuit? LUl-ttlJ TI1~ C/J.(2Il.!ttJ 7 i=l.OlJ.J! W ''''~ A-~ t:s. ~"'A,NLl!' /...~, T AJE,b. What's the purpose of a fuse or circuit breaker?

~ ?12.. !ut!4Jr 70tJ MuLfo{ adLf2 ~r FU;iI1 G.()II.J~ fH~/(c. What's the current in a l4-ohm t9aster when~"t' eo to a l20-volt circuit? "Ii! t.ulrr=< f2..": 'V';:- .r= T.:' {201/ S. {,A- (C/Jiltd. Calculate the resistance oTthe filamenUff"tJig t carries 0.4 Awhen 3.0V is C~;;impressed across it. I =/\ 11.d. V IIc~r:Ju "frr ~~.of e. =?

i2-.: '!:::= 3.()Y;;J- 0.'1<.7.S".;a;;

~n..J\4I" l

tSoi1'# t..J

IHI..

r20V

4. a. Calculate the equivalent resistance of this circuit.:30,5L

b. What is the current in one of the ten-ohm resistors?

d. What resister consumes the

most power? The least?e.=~ 2V

oJ..v= I;2. c: (z..7ii2:!)

~

5. a. Calculate 'went resistance of this circuit.

b. What's the ~n the circuit?llv' £] 1~ ,?-" 'L:.J::~::-- =JiB L..- 2.n. J S..n. ~

c. Calculate the voltage dr<fP fl. If. ~ • ~- ---'~~ In

across the three-ohm resistor.

1) The net direction in which electrons flow through a circuit is:(a) the direction of the conventional current. ~v'(b) opposite the conventional current.

6. a. Calculate the equivalent resistance of this

circuit. 1'2 .S.sz-b. What's the. total cu~rfnt iQ the circuit?

i2-.: V J:'.::' 7r • c..s- ~ = t~ \c. What is thfpower I~st in R2? (l.r SL ,~

P :'r 2 ;2. :: () A ')' (S-.a.j-=i!o ~ 7Batteries and Direct Current

-=- 25V

---

R,=SO

50

Answer: (b)Oiff:/

Answer: BOift:1

Current and Drift Velocity

Answer: BDiff:1

iA

Answer: CDif/: 1

Resistance and Ohm's Law

6) Consider a current moving from left to right through a resistor. Which end of the resistor is at higher

potent~ial?Ieight

C) indeterminate, depends if current is charging a battery or discharging a battery

Answer: ADift: 2

Answer: CDilt" 1

c.~~eJ £'!.P~~''jOt....~~L4-.w

18) Consider two copper wires. One has twice the length and twice the cross-sectional area of theother. How do the resistances of these two wires compare?

Both wires have the same resistance.B) ance of the shorter wire.C) The longer wire has four times the resistance of the shorter wire.D) The shorter wire has four times the resistance of the longer wire.E) The shorter wire has twice the resistance of the longer wire.

Answer: A Wider = l,,~~rc.s.~"fzu...ce.Di!!: 2 L"1\.9U"':: h,~h.ev re.~,'!..htl1.t.(.20) A device obeying Ohm's law must have a resistance which •

A) is proportional to voltage.B i ional to current.) is constant.

Answer: CDiff:/

22) A potential difference (V) is applied to the ends of an object causing a current (I) to flow through itIf the object obeys Ohm's law we can obtain the resistance by

A) multiplying current by voltage.B) dividing current by voltage.C) calculatin 12V.

IVI mg voltage by curren.

Answer: DDiff:/

24) What potential difference is required to cause 2.0 A to flow through a resistance of 8.00?

Answer: 16'vDiff: 2

~ =- ~. 0 ..52.. If~ -;:

Ii.:: r (2. -:: @.0 fir y.. fJ..o .9-tN,?;25) Electr' . tance has units of

A) ohms.mperes. ~

C) volt-amperes. ~ '-D) O-m.E) (O-m) -1.

Answer: ADiff:/

17.4 ElectricPower

1) If the resistance in a constant voltage circuit is doubled, the power dissipated by that circuit willA) increase by a factor of four.B) decrease to one-fourth its ori inal value.

decrease to one-half its original value.D) Increase y a ac or 0 o.E) be unchanged.

Answer: COiff:2

2) A home appliance is rated at 250. watts connected to 120. V.(a) What current does it draw?(b) What is its resistance?

)Pr11ow many kw-h does i~use in one 24-hour day?"'Or '11. '»Iit\ @-11~~@.ro'NY!.J.,.)! \

Answer: (a) 2.08 A :; I(i(loow)(b) 57.60 = '0() ~W.h....(c) 6.00 kw-h

Oiff: 3

Answer: DOiff: 1

I=:Q..: ?

p=IV.;;. 7 16

.p ~ =- ..e. =?C'O vJ .J27;./r'I{ t"UJ If L:..:::.JP~I 'l~ 12..:-....L _ UZl tel

J: I. - (Z.IA- ~

=sSlJ

~.::rv'r =-L= I. "IY1~1JoI

V IZO V

~( IJ. 3.sz...

and bum up before very long.

,C) It would barely work (or maybe not work at all), since the voltage here is too low to push

nough current through the device.

volt

4) Consider a 1.40kW hair dryer operated on 120. v. What is(a) ~he cu.rrent? ?=- 1.4~lu1W V:: 12.0 V(b) Its resistance? ,

2,=, 1:=7~ p.::.f 1. R. _£_u~,,~'j"-

It- - f' - 1f~)"O\J8) Appliances in the USA are designed to work on 110-120 V, whereas appliance urope operateon 220-240 V. What would happen if you tried to use a European electric shaver in this country?

A) It would probably work as well as it does in Europe, since it is the power rating, not thevoltage rating, that mailers.

B) It would probably work as well as it does in Europe, since it is the current rating, not the. .

Answer: (a) 11.7A(b) 10.30

Oiff: 3

E) This question cannot be answered without knowing the frequency used in Europe and in theUSA, since this is the parameter that mailers most in any electrical device that operates on alternatingcurrent.

Answer: COift: 2

14) A 200. a resistor is rated at 1/4W.(a) What is the maximum current it can draw?(b) What is the maximum voltage that should be applied across it?

Answer: (a) 3.54 mA(b) 7.07 VOift: 3

15) Electric power has units ofA) ohms.B) a-m.C) amperes.

Cll:icilt-amperes (watt) IEj1n-m) -'.

Answer: 0Oift:1

16) A lamp uses a 150.W bulb. If it is used at 120. V, what current does it draw and what is itsresistance?

Answer: 1.25 A; 96.0 aDift:2

17) In the graph shown, what physical quantity does the slope represent?

A) currentB) energyC) resistivity0) conductivityE) resistance

p(W)

v (wob)

Answer: ADiff: 2

V =(60V

=~OW~{()OV~

p= -.S2PQ tU

Answer: CDiff:2

18) A 500-W device is connected to a 100-V power source. What current flows through this source?A) 50,000AB) 200. rn

. 0O.OA

E) 1.60 x 1018electrons/s

Resistances in Series, Parallel, and Series-Parallel Combinations

18.1 Resistances in Series, Parallel, and Series-Parallel Combinations1) This is a symbol for which of the following?

Answer: BDiff: 1

= 6.0 volts

Answer: (a) 9.6 0(b) 11 0.63 A, 12= 0.45 A, 13= 0.18 A

3) R1 = 5.6 0, R2 = 5.6 0, R3 = 14. 0,

For this circuit find:(a) the total resistance connected to the battery.(b) the current in each resistor.

2) In 5.0 minutes, 500. Coulombs pass through a 24. ohm resistor. What is th potential across theresistor? r: -i:- - ~c. S ~ R..:: J!~ - =- f2. =2.I.{.sz- ~ oX

A) 300. V CF.o"~s/""\j 3 It- r .:-~.:"ft&6.~~ R:~ ~6lCf30.v I 'iJ,:r~::6."s",.:i5'.,S0D) 400. V (, e 3Sv'E) 35. V v::;r~e~.1~t{.5Z- x=: CftJV ~c V.=V,,= '.~.J'""

Answer: B ., Si?-. = 2SII

~'II-H+'a... "1. ~ ~ ., I(~)) J1i.jO~l@~ tS'.~.st

(j) ", ~ f~Jf,< (V~E -=- Rz'!:.~cttt~iri

f.~~I:(sz-

Dift: 3

8) An air conditioner uses 2000. watts at 120. volts. What is its current and resistance?

~':-2 '!=-'loV +""~ \2=7;' - v~Answer: 16.7 amperes and 7.20 ohms Oro vJ P - IfOift: 2 ~ :1' 'J ...L ~ .t.._ ~ D ~ VZ _0.2(ji,?

V 120'( "" t.7/r f-"""p> ~9) Why does a lamp burn out quicker if it is turned on and off many times, rather a one that IS left 7.l.R)burning? !

Answer: The Tungsten filament has a positive temperature coefficient of resistance. Thus when it isfirst turned on, its current is excessive and the filament for an instant evaporates some of its surface,thereby becoming thinner.Oift:2

10) Two resistors in series equal 9.0 ohms total; but the same two resistors in parallel are equivalentto 2.0 ohms. What are the resistor values? e.(Q" RA i ~ ~73- i1-At '7 -Il..aAnswer: 3.0 and 6.0 ohms --L _ l t 1 .L- ..l-.. + IOili 2 ~(<\. L Rp. ~~:: 2.. () 5L R.et{ - '"ea i:11) In order for the human body to conduct 100. mA or more, connected to 120. volts, its resistancewould have to be less than what? ~:: Y...:. }..201) {

kQr {()()X{()-3.&- - (2- 00 .RJ

Answer: 1.20 'l" ~~

Dift: 2

Answer: 303. QDifJ: 2

13) What resistance added to 633. Q in parallel would produce an equivalent 205. Q?

.L , .l .•.1. J J... i 1. ; ~ - 0 ~eC(, i<1\ Cd Z.CSS/.. - bS~ e It e.e - I :33a

9. 66'fB~ O.Gulse _.L. C2e. c 3~JJL -SL - ,~C> _0

15) My hair dryer is rated at 1500. watts and my television only uses 100. watts, so why do I paymore for electricity for my TV than for my hair dryer in a year? ~

Answer: One pays for energy, not power. I use my TV so much longer that its energy usage (power Xtime) is more than the hair dryer. ------------DifJ: 2

Q~flSL+lrCl~l \~lAe~. IP !n.lt<""c.l'~

t!AOrc. (a. "1 yu ~'\I.b"j k. 6.2 I Q~Answer: B

16) A 3. Q resistor is connected in parallel with a 6. Q resistor. This pair is then connected in serieswith a 4. Q resistor. These resistors are connected to a battery. What will happen if the 3. Q resistorburns out, i.e., becomes an infinite resistance?

A) The current in the 4. Q resistor will drop to zero.The curren In e. resls or WlllTnC~

e current provide yea . c ange.D) The power dissipated in the circuit will increase.

DifJ:2

17) A metal wire conductor would pass less currr~ if itsA) length were decreased. tJ6TB) cross-sectional area were larger.

con uctlvit were sma Ier.-eSls Ivity were smaller.

Answer: CDiff:2

7

18) One terminal of a battery is connected to a closed circuit, while the other terminal is leftunconnected. Which of the following statements is true?

(Al No current flows through the batte!V..J:lru:L1hap.o.tentialof any point in the circuit is the same.B) No current flows tlirough tfie battery, and the potentials of different points iiiltTe-eif .

different.C) Current flows through the battery, and the potential of any point in the circuit is unchanged.D) Current flows through the battery, and the potentials of different points in the circuit are

different.

Answer: ADift:2

Answer: COift: 2

23) In the water flow analogy, the height of the water is analogous to what electrical quantity? Also apump is analogous to what? V

uLi"44CAnswer: potential (voltage); a battery (or emf)Oift3

24) When resistors are connected in parallel, we can be certain thatA) the same current flows in each one.caDfie potential difference across eaCh ISthe same;::::> (101 tz;1=.C) the power dlsslpatea in each ISthe same. ----D) their equivalent resistance is greater than the resistance of anyone of the individual

resistances.

Answer: BOift 1

25) A 3.0 0 resistor is connected in parallel with a 6.0 0 resistor. This combination is connected inseries with a 4.0 0 resistor. The resistors are connected to a 12. volt battery. How much power isdissipated in the 3.0 0 resistor?

A) 12 WB) 5.3 W ~ 0 ( 6" e,X'1IYJ,C) 7.7 WO)6WE) 2.7 W

Answer: BOiff:2

-

Answer: BOiff:2

27) Two 4. 0 resistors are connected in parallel, and this combination is connected in series with 3 O.What is the effective resistance of this combination~ -

~ £;t 14>1-\~0) 1.20 -t-,;J: J )E)4.0 3st.. ~ (~ : .L"l1'-> tg,... eA 12e

=J... t~

\ '1~ '13-~c~= 2.CL -') (,() ~l$L

28) Two 100W light bulbs are to be connected to a 120V source. What is the current, potentialdifference, and dissipated power for each when they are connected: It-:; ':i- _

(a) in parallel (the normal arrangement)? \) -r:.V .J..- -(b) in series? £X'7J.". - p

'"=f:..YJ.JP 1:". ~ - ~ 'Oall _~ .Answer: (a) 0.83 A in each; 120 V; 100Weach, 200W total. V i"~;v-~ I••.~.. (b) 0.42 A in each; 60 V; 25W each, 50W total. /2.,,11 - fJ"Y'./{ •.( &atlt 100•••••

01ff: 3 'Z. ~ z«) Lv I'l> 71i-(..

29) A combination of 2.0 0 in series with 4.0 0 is connected in parallel with 3.0 O. What is theequivalent resistance?

Answer: 2.0 0Oiff: 2

30) Four 20. 0 resistors are connected in parallel. What is the equivalent resistance? 1 . .:L.~7;W;~ t 1,=1'"~I,"ll,~~'~.t ,t +t. ";;~-<

eet • ~W"- + ~ t-L.. f-~~31) The lamps in a string of holiday lights are connected in parallel. What happens if one lamp bumout? (Assume negligible resistance in the wires leading to the lamps.)

A) The bri btness of the.lamps-will not change appreciably.e other lamps get dimmer eqoatl .

C) The other lamps get brighter equally.0) The other lamps get brighter, but some get brighter than others.E) The other lamps get dimmer, but some get dimmer than others.

Answer: AOiff:2

32) As more resistors are added in parallel to a constant voltage-source, the power supplied by the

source D V~ I IA) increases. r = I') K.. G I r... P (L.'{(l.l e 1<.4 Q.-,B ecreases. ,-e) does not change. ~ IJU o..JJ i'C..<:'I\~I'o('~.0) increases for a time and then starts to decrease. ~" o.t R 4,

Answer: AOift 2

~\:)t:.lll,tj; R~~(~lbtt.J i",S ~It I(!J I I\. c ttl!t}.st!~it-a IS,!7-lNCt .

t~es-ne ange.~eases.C) in0) increases for a time and then starts to decrease.

34) As more resistors are added in series to a constant voltage source (zero internal resistance), thepower supplied by the source

Answer: BOift: 2

35) A 6.0 n and a 12. n resistor are connected in parallel to a 36. V battery. What power is dissipatedby the 6.0 n resistor?

A) 48.WB) 12.WC) 486'w~~~

~Answer: EOift: 2

36) A 6.0 n and a 12. n resistor are connected in series to a 36. V battery. What power is dissipatedby the 6.0 n resistor?

A) 216'w '4."1"B) 486'w

~. ...r:::-'V'<'~9) $(,:{ ..:::- {;R. \UL

8.W l__ ----Answer: 0 ~

Wff2 >bV4~J

38) Three identical resistors are connected in parallel to a 12.V battery. What is the voltage of anyone of the resistors?

A) 36. V

~~

~E) 3. V

Answer: COift 1

~ Ci'l'~U e { - fN)QVlC ~ it ~ SCiwtQ

V 0 ( kje. f2. V

39) When two or more resistors are connected in series to a battery~

A) the total voltage across the combination is the algebraic sum of the voltages across the. dividual r s'sto

B) the el'i~lent resistance of the combination is equal to the sum of the resistances of earesistor. AA . u.6-

19Jhe_same current flows through each resistor.0) all of the other choices are true.

Answer: 0Oift:2

40) Three identical resistors are connected in series to a 12-V battery. What is the voltage acrossanyone of the resistors?

A) 12 VB) 3 VC) 36 V0) 0 VE) 4 V

Answer: EOirl: 2

.--Answer: BOift: 1

Answer: DDiff:J

A) middle resistorB) resistor closest to the batteryC re .s10 fartbes o.Jbe.batle

none, currents are the same

42) Three identical resistors are connected in series to a battery. If the current of 12 A flows from thebattery, how much current flows through anyone of the resistors?

~~0Cu.~-t s.uVl-\.~ I "- Se.V'l~gl~4\ KCs. 6rc0.E)6.A

Answer: AOift: 1

43) If entical resistors re connected in parallel, and a battery is connected as shown, which resistorwill have e a s current flowing through it?

I?:;~'l- I _V?,~

-(t ~~44) When two or more resistors are connected in parallel to a battery

A) the voltage across each resistor is the same. T('tu.~B) the total current flowjng from the battery eq~als the sum of the currents flowing through

each resistor. ,(lUI!' L~fL.QM,. (HI'\- I'" (.)C) the equivalent resistance of the combination is less than the resistance of anyone of the

resistors. \t\Lu.~ -D) all of the other choices are true.

Answer: DDift: 2

Diff: 2

12) This is the symbol for aA) ground.B) switch.C) fuse.D) capacitor.E) resistor.

Answer: BDiff:1

13) This is the symbol for aA) battery.B) resistor.C) capacitor.D) fuse.E) switch.

Answer: COiff: 1

1 ) This is a symbol for which of the following?A) galvanometerB) voltmeterC) resistor

CJ?~~e~Answer: EOiff:1

2) A current reading is ob ined by properly placing an ammeter in a circuit consisting of one resistorand one battery. As a resultA) the voltage drop across the esistor increases. ~ 0i c>}..) ~1C11--n.,BJJbe-GurrenHlowinginihe-Gir' increas.es

the current flowing in the circuit creases.D) the current oWing In the circuit'do no change.

Answer: COiff: 2

10) This is a symbol for which of the following?A) galvanometerB) voltmeterC) ammeterD) fuseE) ground

Answer: BDiJf: 1

Answer: 0DiJf:I

18.5 Household Circuits and Electrical Safety

2) When double-checking a wire which is assumed to be not "hot", you might see an electrician"testing" for electricity by briefly touching the suspicious wire WITH THE BACK OF THE HAND. Whydo you suppose the front of the fingers are not used?

Answer: If current flows through the fingers the muscles are likely to contract. If the front of thehand were used then the hand might be clamped to the wire, but using the back of thehand prevents this worsening of the situation.

Diff: 3

8) The usual household fuse or circuit breaker is rated at~OpA.15 A.

D) 20 mAoE) 200 A.

Answer: BOiffl

10) Why aren't houses wired with outlets in series instead of in parallel?

Answer: Unless all circuits were being used, none would operate. Also all would have to use the

s~me current. () ~ s -r:: l P 1- lDfft:2 '\:- ~,O --, f"IIJ 'V ~1I't...tl el.I ~ Lt{.\

\ V\.. a'PI/\~ c.¥ I ,,~r"l. "J11 ) My electric razor operates on 120. V and requires 3."0Amperes. How much current comes outafter delivering 360. walts of power? -r- _7 'e-::. 1/

A) 120/3.0 A 4- p~r VB) O.A -r :::~:: .3,~lttr/J~ ~ v ----E) 2.4 A

Answer: CDiff: 117) This is a symbol for which of the following?

A) resistorB) ammeterC) voltmeterD) fuseE) galvanometer

Answer: DOJ,,: 1

Answer: AOJ,,: 1

3rd wire on a 3 prong plug is connected to

TO ~hV"W E:.,,«(..CS.s

CftARG Cr to Go TO

life. eA~TH19) A "blown" fuse has

A) moderate resistance.B zero ~istal'l .C) in mire (very large) resistance.

Answer: COjf/: 1

S 10fSa Pl.-OW ()F

~ L Cc Tf-l t.ITL;.