Download Exam II - Physics

Exam 2.00
REMOVE THIS COVER SHEET ONLY WHEN
TOLD TO DO SO. MAKE SURE TO PUT YOUR
NAME AND SEAT NUMBER ON THE FIRST PAGE
OF THE EXAM BEFORE YOU TURN IT IN.
4 March 2008
College Physics II (PHYS 2020)
Adam Johnston
General Formulae:
Fnel =
ma,
2 +2
w=mg,
Specific Formulae:
-
-
F=qE,
F
=
qvBsin8,
F
=
IeBsin8,
L =
V=IR,
NIABsin8,
<l>
=
BA cos¢
f
=
-N il<l>
M
1fT
=
2n YLC'
c =jA,
Constants and conversions:
22
P=IV
B= !-to I B = N !-to I B = 110 N I
2R '
r'
L
2:rcr'
Vp
£
=
Np
Is
-=-=-
£ = NABw sinwt,
E=cB,
Poem:
31
me = 9.11 x 10- kg
mp = 1.67 x 10-27 kg
lei = 1.60 x
10-
19
C
= 8.85 x 10- 12 F/m
k = 8.99 x 109 N m 2 I C 2
EO
!-to = 4n x 10-7 T . m I A
1 hp = 746 W
c = 3.00 x 10 8 m/s
Advicellnfo:
Welcome to your second exam of the semester.
Please keep head, hands, and feet inside the
vehicle at all times. Show your work clearly for
full credit. Ask questions if you have them.
Circle your answers if you want me to find them.
Don't feed the bears. No camping within 100 feet
of a watershed. All numeric values are good to 3
significant figures. Have fun. You should have
three (3) pages in this exam, not including the
cover sheet. 100 points are possible.
Happiness
So early it's still almost dark out.
I'm near the window with coffee,
and the usual early morning stuff
that passes for thought.
When I see the boy and his friend
walking up the road
to deliver the newspaper.
They wear caps and sweaters,
and one boy has a bag over his shoulder.
They are so happy
they aren't saying anything, these boys.
I think if they could, they would take
each other's arm.
It's early in the morning,
and they are doing this thing together.
They come on, slowly.
The sky is taking on light,
though the moon still hangs pale over the water.
Such beauty that for a minute
death and ambition, even love,
doesn't enter into this.
Happiness. It comes on
unexpectedly. And goes beyond, really,
any early morning talk about it.
Raymond Carver
NAME:
Exam 2.00
4 March 2009
College Physics II (PHYS 2020)
Adam Johnston
~-( ~..J~Q.....
SEAT:
SCORE: \ "b 0
1100
Multiple choice: Each question is worth 5 points.
A n e ectromagnetIc wave, a so known as "I'I~ ht, ".IS composed 0 f
C. a constant electric
A. an oscillating
electric field only.
B. an oscillating
magnetic field only.
field and an
oscillating magnetic
field .
D. a constant
magnetic field and an
oscillating electric
field.
~~.
oscillating
magnetic field and an
oscillating electric
field.
. fiIeld Th e k'InelIc energy 0 f the charge WI
A charge IS mOVIng throug]h a magnetic
2
B. decrease.
A. increase.
3.
@emain constant.
D. More information is
needed to complete this
sentence.
Imagine that you are holding a magnet with the magnetic field pointing into the page. Below the magnet, in the plane
of the page, is a loop of wire. As the magnet is moving upward, away from the loop, in what direction does an
. duced current et roduced?
lockwise (as
from above the
loop).
4.
I
B. Counterclockwise
(as viewed from above
the loop).
C. No current is
produced.
D. More information is
needed to answer this
question.
E.42.
Imagine that you are holding a magnet with the magnetic field pointing into the page. Below the magnet, in the plane
of the page, is a loop of wire. As the magnet is moving upward, away from the loop, in what direction does the
eI
oop·.
')
~agnet tiee I a tiorce pro d uce db)y t h
.
~own; opposing
e motion of the
magnet.
B. Up; the same
direction as the
motion of the magnet.
C. Left; perpendicular
to the motion of the
magnet.
D. Right;
perpendicular to the
motion of the magnet.
E. None of these.
5.
A. North
6.
B. South
D. East
E. None ofthese.
A transformer utilizes two coils of wire, each connected to its own circuit. They are close enough to one another so
that the magnetic field of the primary coil is detected as a flux within the secondary coil. If a constant, direct current
(DC) is flowing through the primary coil, then the secondary coil will have a resulting
A. constant, direct current.
B. changing, alternating
current.
,(c)ro
current.
D. None of these.
NAME:
~.
C I¥Z...J( ~
Situation I: Staying current with physics
A. [20 points] Adam has a rectangle of wire with a resistor in it. The rectangle's original dimensions are 5.00 cm tall by 35.0 cm
wide, and a constant magnetic field of 10.0 T is producing a flux straight through the area of the rectangle. But, over a time of
0.0250 seconds, Adam pulls the wire until the rectangle's dimensions are 20.0 cm tall by 20.0 cm wide. How much voltage is
induoed .em" the ,esisto' in the 'be while Adam ~ling the ,ectangl~
t
=- ~"
Pi-
~~--,
-~:~
~~
..-
II -AI"",
( +\.Ir
'
\
"J
~~+
--------
B. [20 points] An electron, with a mass and charge magnitude described on your cover sheet, is moving with a kinetic energy'of
4.10XlO-18. J in a clockwise circle that has a 5.9.Q.SIJ1._radius. Calculate the magnetic field that must be present fo~o happen,
and desc~, ibe its direction.
I'"
,)
'.
/
r\'- 'I lJ<... --
_\lli,~
-;
"-"
"2
...~
•I
~:.
\~2
~
--vA.
.,1
~
'-
_
'(":.~
O~ ,If'\..
I
)
Situation II: Some light problem solving and another attractive problem
c. [10 points] Initially unpolarized light passes through two polarizers. First, it is transmitted through a polarizer that is oriented
60.0° with respect to a vertical axis, and then it is transmitted through a polarizer that is oriented at 35.0° with respect to a vertical
axis. What fraction of the original intensity is transmitted through the polarizers?
,~
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C;~
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"')"i ,=.. ---:r::'
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:: EX", =-X/"'?- 2'~.:'~
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\.....ct 4'''\ W~ 0
c, Co ~ ~d:"
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<>
t." ';;;
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"
D. [10 points] Because he so likes to do physics experiments, Adam is shaking a positive charge back and forth, left and right, on
this page. Show and/or describe where you could place a loop of wire that would detect the magnetic field in a wave resulting
L.. "~ 010?..;....I .\ ,~,,>
Jf'
',:..
t' .",,!..
from this action.
\
':>
,'
, "",
,,, ~ ~
.I:::- \
-
?
J
.\~
~~.
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'0ef(' w~ ~'c.!~~'
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,_.
: . ' (\
,.\"" e ~~.t.-
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fil
f\ \~
\
t,
,...,.n
A
\ ,",,';;
() l'~
\. \"" t.. ( V_ \
C ~ ..\'\t.,c.. ::;t,1!- J ",...F\\""
1\ .... ,
<.A.
Q\~"~ ?:,(~\I .. \ '.-;\'t>
.,;;::. "'I"'.\\~jI.~4.
faD ~ "'\... k.•..., it -\;'( I <J I' \. ...,
E. [10 points] Two parallel wires are 0.300 m apart from one another, and each wire has the same amount'of current (2.00 A) going .... k. Co t:'
"\
13
I
through it in the same direction. What is the total magnetic field exactly halfway in between the two wires? (The magnetic field.2\.:-<- )
produced by a single wire is described by the equation, B
= J.lof .)
2m-
rpe-.f! •