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Phys
Exam
November14,
n t l
urr,le Js
lq-fiol,ts
StudentLD.
Number
k = -
l-
= 8.gg xlosNm2/ C
lre "
t"
= 8.85xl0-
F /m
e = 1.60x
t'g
C
m" =9.11x10-3t
kg
m
p
x l 0 - 2 1k g
/ ' t o = 4 z x l \ - ' H / m
c = 3. 0 0 x 1 0 8 m / s
Keepin mind
thatI mustbe
ableto follow yourwork
in orderto giveyou
credit. This is especially
true
whenawarding
partialcredit.
A wronganswer
with theright
methodsgetspartialcredit.
If I cannot
figureout
rhemethods,
thenno credit.ShOW
VOUf WOfk!!
Units!
Units!
Units!
I
( l5 pts)Belowis a circuitdiagram
with h.voresistors, a switch,emi andan inductor aslabeled.All answers mustbe
iustified.
a) At time zerothe switchS is closed.
Calculate the cunent12attimezerojust afterthe switchis closed.
AJ{."
- r*t-[.]
clutr, 13 t, t,-'1..*r....rlg
I
: \ -
l t v
6.r1-o-
t. fr^
n
J ,
R , rR ,
b) A voltmeter is attachedacrossthe inductor
with th€ red.l€ad on the risht hand side and
the black lead on lhe left hand
side. What is the readingofthe voltmeterjust after the swit"h is closed?
Fr^-
Kt r.Ll^.*|, r,rr raaur
j
L.,^..
.
I V- I =
- Bt
I V. | =
lt. ts-,-n )l r.o-,tsr-)
: 2.Btz
ri
,!:,,n.c *.
i ,^J,.{.JoFoplorc.
{'l.a
ihsrrc sirtn cu"^"-f'
h/q Luro
*0.a
lq-
Jttlq
'0.
+tt
rt6 Lt
lirtr 'avrr'
V. =
c) A long time has elapsedsincethe switch was closed. Calculatethe current1,.
No-
1
fr= fr
V " = o s i r " c e
4 I r = o
= >. f r = D
d i
-.
J , = 9 = l L v. a z.. - 1 ,. A
Kr
-l:\
l$-
:5,01(l
&:
l.slo
d) In thespace belowsketch a graph,ofthe energy storedon thecapacitor (vertical axis)versus time(horizontal
axis).As
usual,provideunits,a numerical
scaleandtick marks
t =
t S= +
S*tt"t
U"**
=
3,12)-
lrrt Pt't
t)
t
(r.)
.a
to
"l
7..
l, ."
3.0cm a
r t t
* ) [
idealsolenoid. The inductor hasa lengthof3.
. L
{
=
l o L
N
s t n t
t
=ft
o3 '*)[?s-i.t
o-3n )
I H n
p d ' n l [
y. o c -
I \
r 4 r , \
P
t
. o f . t o
inductor of25 mH can be thought
ofas an
cm'. How many tums of wire must it havei
L = , M o h n t-. /
l! = I - t t -
of 4.
area
,//t-
and a cross-section
N
n = v
I
l l r n n \ - I
t
n'.-J I
l , A
= l , Z L
r r D
axisofthe filter is
- (15pts)Unpolarized
orientedin an up-down
light of intensity I" is incidenton a
polaroid
filter denoted(a) below.Theoptical
direction.
t
l. \ ) , j
l - , - /
I f b ) / ,
a) Whatis the intensiryofthe light whichgetsti[ough filter (a)?Express youl answer in termsofIo. you mustJustifyyour
answer'
I
=
sintt
(colo) =r
trl
'[l
p.,lt"igr{ttrr
( / q r t r r l r t r r r { r d l t 1 * [.
r ^ ^ p ' l r ' r t l r l '
( i ; t ' U '
b) A second filter (denoted(b) in thediagram) is laid on top offilter (a).what inrensity oflight penetrates bothfilters?Express
you answerin termsof Io.Again,theanswer
mustbejustified.
. I
T
o
J K
s Q t s r g t
; r o l r " t 3 e
r
h a r \ t r.
r K t r
,j&
$t ,nt.
t t
r 1 t r " t L i t ' r t l r z
c) A thfd filter wilh an orientation of 30owith respectto filter (a) is interposed 6etween f\lters(a) and(b). whar intensiry of
light penetratesall threefilters? Again,expressyour answer in termsofl,.
( 4 \
I - r A
J -
. '
o?'-l Io
l,
,j
d) supposefilter (c) is laidon top of filters(a) and(b). what intensity of lightpenetrates all threefilters?
No
irnt,.rt5co-t. +{^UL.$l$r's
4
tr^l L.
To
0
t1-l{t
t,q,... tlU'rcy L
t'
