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Electricity DC Circuits

ANSWER KEY

Section A Multiple Choice Questions

1. c

2. a

3. b

Explanation: Total resistance is 45 x 3 = 135

Current is 50 V135 = 0.370 A

Poer is Volta!e x Current" t#ere$ore" Poer is 0.370 A x 50 V = 1%.51% &

' 1%. 5 &

4.

Explanation: Total resistance (er branc# is )1*30+ = 1*30

,oe-er $or (arallel circuit" resistance ill be t#e reci(rocal o$ 1*0" #ence resistance is 30

Current is Volta!e /esistance" #ence 10 V 30 = 0.33 A

o $or to resistors" total current $loin! in t#e circuit is 0.333 A x 2 = 0. A

' 0.7 A

5. a

. c

Explanation: Volta!e = Poer Current" #ence 10 & 0.5 A = 20 V

7. a

%. a

. a

Explanation: Current = C#ar!e )units is coulobs+ Tie" #ence 10 C 2 s = 5.0 A

10. a

Explanation: Con-entional current as base on t#e isconce(tion t#at current consiste o$

(ositi-e c#ar!es. ,oe-er t#is as $oun untrue" #en it cae to li!#t t#at current consiste o$

ne!ati-el c#ar!e electrons. ,oe-er t#is isconce(tion #as been aroun $or too lon! to be

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correcte" #ence t#e ter con-entional current6 as concei-e. T#e eanin! o$ con-entional

base on or in accorance it# #at is !enerall one or belie-e.

Section B: Short Answer Questions

1a. 1

1b. 4

Explanation: Current = C#ar!e Tie" #ence % C 2 s = 4 A

1c. 0.5

Explanation: Current = C#ar!e Tie" #ence 5 C 10 s = 0.5 A

1. 20

Explanation: C#ar!e = Current x Tie" #ence 2 A x 10 s = 20 C

1e. 2

Explanation: Point an A are t#e sae istance $ro t#e cell. ,ence t#e c#ar!e ill tra-el t#e

sae istance an ta8e t#e sae tie to $lo $ro t#e Point to t#e ne!ati-e terinal o$ t#e

cell.

Current = C#ar!e Tie" #ence 12 C 3 s = 4 A

T#ere$ore 4 A oul $lo $ro Point bac8 to ne!ati-e terinal" e-er secon t#e circuit is on.

Tie = C#ar!e Current" #ence % C 4 A = 2 s

1$. 9alse.

Explanation: Current is sae at e-er (oint $or a series circuit.

2.

/e = )11 ; 7 ; 20+ = 3%

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V3 = /esistance x Current = 20 x 0.31 A = .32 V

Total -olta!e = )3.47 ; 2.212 ; .32+V = 12.00% V

' 12 V

As a c#ec8 o$ t#e accurac o$ t#e at#eatics (er$ore" it is ise to see i$ t#e calculate

-alues satis$ t#e (rinci(le t#at t#e su o$ t#e -olta!e ro(s $or eac# ini-iual resistor is

eual to t#e -olta!e ratin! o$ t#e batter. Vbatter = >V1 ; >V2 ; >V3.

3.

/e = 1B)1*11+ ; )1*7+ ; )1*20+D = 0.352 )roune o$$+

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/e= /2 ; /3= 1B)1*3+ ; )1*+D = 2

/tot= /e; /1; /4= )2 ; 4 ; 2+ = %

&e s#all no treat t#is circuit in a series $as#ion #ence$ort#.

Current is sae at e-er (oint $or a series circuit.

Vbatter = >V1 ; >V4 ; >V5?

Vbatter = >V1 ; >V4 ; >V5?

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