Physics 2220
Fall 2012
Paolo Gondolo
EXAM 3
PLEASE FILL IN THE INFORMATION BELOW
Name (printed):
Name (signed):
Student ID Number
Discussion Instructor:
U __ __ __ __ __ __ __
Chad
Chris
Peter
Physics 2220
Fall 2012
Paolo Gondolo
Data: Use these constants (where it states, for example, 1 ft, the 1 is exact for significant figure purposes).
1 ft = 12 in (exact)
1 m = 3.28 ft
1 mile = 5280 ft (exact)

x


x 2  a 2 dx 
1
3

x2  a2

3
1 hour = 3600 sec = 60 min (exact)
1 day = 24 hr (exact)
2
2
gearth = 9.80 m/s = 32.2 ft/s
gmoon = 1.67 m/s2 = 5.48 ft/s2






dx
 x2  a2 
3

x
a2 x2  a2
1 year = 365.25 days
  ax
e
dx


1 kg = 0.0685 slug
1 N = 0.225 pound
1 horsepower = 550 ft‫ڄ‬pounds/s (exact)
24
Mearth = 5.98 × 10 kg
Rearth = 6.38 × 103 km






Msun = 1.99 × 1030 kg





Rsun = 6.96 × 108 m
22
Mmoon = 7.35 × 10 kg
Rmoon = 1.74 × 103 km
G = 6.67 × 10-11 N‫ڄ‬m2/kg2
9
2
2
k = 8.99 × 10 N‫ڄ‬m /C





εo = 8.85 × 10-12 C2/(N·m2)
eelectron charge = -1.60 × 10-19 C
melectron = 9.11 × 10-31 kg





μo = 4π × 10-7 T‫ڄ‬m/A (exact)
N(Avogadro's No.) = 6.02 × 1023 atoms/gm‫ڄ‬mole
26
= 6.02 × 10 atoms/kg‫ڄ‬mole
cos(a ± b) = cos a cos b ‫ ט‬a sin b
xdx
 x2  a 
2 3/2
xdx
a2  x2

1
x2  a2
  a2  x2
dx
 n  x  x 2  a 2 


x2  a2
1  a  x 2  a 2
  n
a 
x
x x2  a2

dx
x a





x
x
 sin 1   , or  cos 1  
a
a
a2  x2
xdx
2
2
 x2  a2
dx
sin(a ± b) = sin a cos b ± sin b
mproton = 1.67 × 10−27 kg
h = 6.64 × 10-34 J
π = 3.14
8
c = 3.00 × 10 m/s









1 Tesla = 10,000 gauss (exact)
ρ(H2O) = 1000 kg/m3
1
  eax
a









dx
1
 n  a  bx 
a  bx b
dx
 a  bx 2

1
b  a  bx 
Physics
Physics2220
2220
Fall 2009Fall 2012
Name: __________________________________
Unid: ___________________________________
Discussion TA: ___________________________
Exam 3
Paolo Gondolo
1
Show all work!! Report all numbers to three (3) significant figures.
The 10-cm wide, zero-resistance slide wire shown in the figure is pushed toward the
2.0 Ω resistor at a steady speed of 0.50 m/s. The magnetic field strength is 0.50 T.
(a)
(b)
(c)
(d)
[10 pts.] How big is the pushing force?
[10 pts.] How much power does the pushing force supply to the wire?
[10 pts.] What is the magnitude of the induced current?
[10 pts.] (2 points for the correct answer and 8 points for explaining your reasoning clearly and correctly) What
is the direction of the induced current? Specify clockwise or counterclockwise.
Physics2220
2220 Fall 2009
Physics
Fall 2012
Name: __________________________________
Unid: ___________________________________
Discussion TA: ___________________________
Exam 3
Paolo Gondolo
2
Show all work!! Report all numbers to three (3) significant figures.
An electric oscillator is made with a 0.10 μF capacitor and a 1.0 mH inductor. At t = 0.0 s, the capacitor is maximally
charged to 5.0 V.
(a)
(b)
(c)
[11 pts.] What are the maximal energies in the capacitor and in the inductor?
[11 pts.] What is the maximum current through the inductor as the circuit oscillates?
[11 pts.] What is the energy in the inductor at t = 31.4 μs?
Physics
Physics2220
220
Fall 2009Fall 2012
Name: __________________________________
Unid: ___________________________________
Discussion TA: ___________________________
Exam 3
Paolo Gondolo
3
Show all work!! Report all numbers to three (3) significant figures.
The maximum electric field strength in air is 3.0 MV/m. Stronger electric fields ionize the air and create a spark.
(a)
(b)
[20 pts.] What is the maximum power that can be delivered by a 1.0-cm-diameter laser beam propagating
through air?
[7 pts.] What is the maximum magnetic field strength in such a laser beam?
Ph~sics
22211
Paolo Gondolo
Fall 2(112
Name:
Rhet+
Unid: _ _ _ _ _ _ _ _ _ _ __
1
Exam 3
Discussion TA: _ _ _ _ _ _ _ _ __
Zero-resistance wires
\
Show all work!! Report all numbers to three (3) significant figures.
~L
The 10-cm wide, zero-resistance slide wire shown in the figure is pushed toward the
2.0 n resistor at a steady speed of 0.50 mls. The magnetic field strength is 0.50 T.
x
L
x
x x x x x x
Push
2.0n
x x x x x
0.50 mls
(a)
(b)
(c)
x
0.50 T
x x x x x x
Cd)
:.
--- =
p ~ 11. R
po..tf
I
-I?. -
R
-
B- t-;el~
Th"
-
showt\. I~"
~. ;'V.1)( O.toM) (0. ST)
2-11
0.1\
e')(+eI"A~'
- C§L5 A)
-t,'etJ tk~+- I~ ,'Il!apeAJer\+ o~ +~e loop. The Clt'W.~1
M.tla
+~t \'n,o\ u.c.e~ CIwl ~ r\'t, The
n. e..\- ,'c .+: I"" 'J( +ht-o"1l.\ +- ~ e. 100 f I s J.ecte.o.s I'~
+"-t. po.jt. bec.o..u..st +~t loop o.t"e.o. ~.s Je.c..t-rz.o.5 1A.j lNote thA+ +ke l~ktlt,J
hQ.5
11\+0
B-.f'tl~
flv...)(
~ c.ko..J\~f,). T~~ If\.JIA.Ce.J c.urtfA+ wHl oppose, +-ht c.~o..l\.~e-i1
by cf'e{)'+;Il~ 0-1'\ i"c.\I.tt:.eJ 13 -tlelJ ;'" +~t. $a.Me J:r-e,:I-,'oA 0.$ +lu.
e'lC-\-ert\&4-.\
ThIS
-
vLB
£
:;.
Or'\~
0....,
JOt.6
+.'elJ,
retU--It'es
LAS; (\.<)
+-~t
wk~"h. ,'ftC,t-eA..se.s +h.e. flet
(A
G\OGkW~5e.
n5h+ - ~CVJ. - N. \e , fllA..)C
ok>
Oppo:>e.. +-he' J.ecr-eo...s~,
a~I"e.(;\-~1\. +-ar· +~e. ~f\.lu.ceJ, c-~tt,etl\+ I·
Ph~sics
2220
Fall 2012
Paolo Gondolo
Name: ___
Pe_t_e_r_ __~_e_ro_n__
c,_'k_ _______
Vnid: _ _ _ _ _ _ _ _ _ _ __
Discussion T A:
2
Exam 3
~---------------­
Show all work!! Report all nnmbers to three (3) significant figures.
An electric oscillator is made with a 0.1 0
charged to 5.0 V.
(a)
(b)
(c)
~
capacitor and a 1.0 mH inductor. At t
0.0 s, the capacitor is maximally
[11 pIS.} What are the maximal energies in the capacitor and in the inductor?
[11 pIS.} What is the maximum current through the inductor as the circuit oscillates?
[11 pIS.} What is the energy in the inductor at t = 31.4 j.ts?
eli":
J
c.c - 2.
c.",rt. _ ..!...(O.JxIO'F).( 5"V)'l..
vtiA )( - 2.
L
~
Jk/o ~'!J:MA.J..
::: l.tz5,c/O-G J ::
(b)
ILL z.
- 2.
H,4)
..t:'HAX _
c'-
~
~
(c.)
2.
=)
£l-f1AX
L
l Hltx --
O.05DA=~==­
___
~ I(f:}; I
HAx
• rAM
(w f: ) = IHAx~"tI<. (1:c.0
Name:
____
~~~4_
_ _ _ _ _ _ _ _ _ _ _ __
Unid: __________________________
Discussion TA:
3
Exan13
~~---------------­
Show all work!! Report all numbers to three (3) significant figures.
The maximum electric field strength in air is 3.0 MV/m. Stronger electric fields ionize the air and create a spark.
(a) (b) f20 pts.] What is the maximum power that can be delivered by a 1.0-cm-diameter laser beam propagating
through air?
.
f7 pis.] What is the maximum magnetic field strength in such a laser beam?
I~.P­
A
'5
-
.~
(~~ Ifr~
~
)
/
,