_-----------
'-•....
Physics 1B(b) Quiz 3
Winter 2010
' f... 'Sf2.
~~
(
'J).D
--:) ~~
Problem
configuration
> ~.
'7
if'-
ret
't:-~
rsion B
-::::=:}
B
~r ~ ~~A
1: I charge up a capacitor C in the following c!nfigurations.
charges the capacitor faster?
(a) A charges u
\
faster than B
I(X)Q
b) B charges up faster than A
(c) Both A and B charge up at the same rate
\
• 1IiN-
=- ~ =-
Cff1'-~
·~r
;:blem
Which
L.
~
LOO
I (X)Jl.
l\
~
-tt
\I
~::!s~.
2 The=tY~:::6
IfI makea lightbUl~
filament from tungsten wire that has a radius of .01 mm designed for a 100 W light
bulb with 120 V, what is the length of the wire I need in the filament?
b' _
~L
"- - -fA
(a) 0.340 m
(b) 0.100 m
_
b
~
_)M ~
(c) 0.679 m
<@Y~
f - A.
P - (fJV)"l. _ 1) =:
--,...
p
=)
L ..NtJ/f
:y!:.(to-Vrf'Y' ([20V)~
1
PP
•.'./
1
i
(5,(P~IO 'aJL'~/(x)W)
Problem
3: When I close the switch in the circuit shown, the capacitor
charge. What is the current in the resistor after 50 milliseconds?
(b) 6.07 x 10-3 A
(d) Zero
J
~
IOV
~
~
£-~R--%--O
At Q )(, T-O
C -/16- Q,.,.q)( -0
~)
c-;1-R.
-t -= SO ""--S
:: 5~(6-Z 5
[x[O-"'F
~025P
V0rcJ-Jr'.1f
r-~
~
(a) 1.21 x 10-4 A
C--
-
--e-.=f2-C
\ 05" ..fL
- ({t(P F
-=-
X to).J1)
o. I .5
Problem 4: Referring to the previous problem, what is the charge on the capacitor
after 100 milliseconds?
lO? MS I
A11~
(a) 5.18 x 10-5 C
0[632 :10-6])
8
(0) 368 xlO(d) Zero
C
y~)
(
Q ~ Q'M l-.e-J Q ::J'OV'(IO-r. Fe)( [\L
[;
Problem
5: I have a 12 V battery with an internal resistance that is low (i.e., r =
negligible) with two resistors R1 =100 ohms and R2=50 ohms. I wire up the components
in two different ways as shown. The power dissipated in the circuits is
~eater
i; A ~han in}3)
(b) the same for both A and B
\\
(c) greater in B than in A
afI )~
-)
'/ Refll
8 ~JJss"
Problem
r:2.,
OPal
;~A~
6: What is the total resistance
a the circuit below?
lOOSL
Problem
7: Immediately
current in R1?
after I close the switch in the circuit shown, what is the
R\ -== [C>O Q
~ero
@\00
(c) 0.20 A
(d) 0.05 A
~-1f
~
=-)
7W~
Q::- Q
I
~C{
== Q
=-')
-1\'
T~
,-t",--O.
Q-
x l \rA4)(
0
( \-
e-o~)
\ ')
:=
0
(OV
? ~~)
2
C':
€--O'%IS) =- ~,32><
/6-1<>
----__ ....J)
c;re.-u..;-t
Problem 8: Referring to the circuit above, what is the charge on the capacitor
A1-\.h
after a long time? Is there a current in R1?
(a) 10-7 C and
urrent in R1
;1-...,
) 10-5 C and yes, there is a current
7
(c) 10(d)
10-5
d--.e.e-, 1-1e-e I -t -'l
in R1
~
')
LX 0'4 ',(
=
C and yes, there is a current in R1
C and no current in R 1
A-tJ- ~~
(2
I \S
<:
c...
C
=-[ ovt IDe,
i 1'-- 0-- ?f~.Q
t+
VJ
IJ!Q
~~f2R-
) - l O.t?C
h9
Problem 9: Use Kirchoff's rules to solve the following circuit. What is the current
through the 5 ohm resistor? (Hint: Start at point "a" and go around each of the loops.
Define a current direction.)
(6..IL
~V
t~V
Problem 10: A long, long time ago when I was young, one of the things at
Christmas that drove me crazy was the Christmas tree lights because very often none
of them lit up. How could this have happened?
(a) I forgot to plug the string of lights in
(b) They were connected
in series and one burnt out bulb opened the circuit
(c
strings were connected
(d) All of these
together
(e) None of these
3
and a fuse blew
CO
I
/2-
vv..Ar.Pi:J
l0.JL
\\
2DV
{t
6; 7JLat~l\on
2
~~~
~;
-
T2- - 0
10 V - rsJ2-}rz
-
UPJL):r1 = D
-:)
2-:r:: \ = 0
2A-
2-
=:=-) cPA - 2C.I\+T~)- 2]:2 - 0
CoA - 2Iz
-
2I2 -0
) CoA -;. ~ I2.
-) lT
0
.LJ A - 2r3
==-)
---)
f2JL- )T2. ::=
~ 20 v - ([oJL )I~ -
p-{
2 :=
\.S- A
J