Download Phy2140 Exam 2 SpSu2..

Name:
Student Number:
Physics 2140: Hour Exam 2
ID: A
Wednesday, June 14,2006
Multiple Choice
Identtfy the letter of the choice that best completes the statement or answers the question.
1. When a 24.0-R resistor is connected across a 12.0-V battery, a current of 482 mA flows. What is the internal
resistance of the battery?
0.02 a
-1.
chi
c.
d.
e.
=IR
A\/= E
25.0 R
49.8 R
76.2 R
g =If?+
s3,
2
E-ZR
=
-6Qn
I r
-
L
2. Three resistors connected in series each cany currents labeled I,, and 13. Which of the following expresses
the value of the total current IT in the system made up of the three resistors in series?
a. IT = I , + I? + I3
- 3. Three resistors connected in parallel have individual values of 4.0,6.0 and 10.0 R, respectively. If this
combination is connected in series with a 12-V battery and a 2 . 0 4 resistor, what is the current in the 10-R
resistor?
I A
---7
u
(a.
b.
c.
d.
e.
Pnmlle(
0.59 A
)
1.0 A
I1A
16A
23 A
I
A
s
-z~=
:
Y.$,
6 4 & few ~ u / r c l s J ,
zor = '% ~r =
/-2y/jb.gyn =
-+I
~
9
ion
I
3,054
=1 j o ~. s ~ ~ ]
+
4. If I/ goes to the right through R,, I2 goes to the right through R2, and 1 3 goes to the right through R3, what is
the resulting equation resulting from applying Kirchhoffs loop rule for a clockwise Ioop around the perimeter
of the cir*
1
--
- 5. The magnetic pole of the Earth nearest the geographic North Pole corresponds to which of the following?
a. a magnetic north pole
a magnetic south pole
c. a magnetlc arctic pole
d. a magnetic antarctic pole
>
6. A proton is released such that its initial velocity is from right to left across this page. The proton's path,
however, is deflected in a direction toward the bottom edge of the page due to the presence of a uniform
magnetic field. What is the direction of this field?
out of the page
2
d.
e.
to top edge of the page
from right to left across the page
from left to right across the page
w
t
o
F
b(.e~
Name:
ID: A
7. An electron moves through a region of crossed electric and magnetic fields. The electric field E = 2 000 V/m
and is directed straight down. The magnetic field B = 0.80 T and is directed to the left. For what velocity v of
the electron into the paper will the electric force exactly cancel the magnetic force?
8. There is a current I flowing in a clockwise direction in a square loop of wire that is in the plane of the paper.
If the magnetic field B is toward the right, and if each side of the loop has length L, then the net magnetic
torque acting on the loop is:
e.
zero.
9. A uniform 4.5-T magnetic field passes perpendicularly through the plane of a wire loop 0.10 m2 in area. What
flux passes through the loop?
a. 5.0 T.mZ
Name:
m
ID: A
10. An airplane with a wingspan of 60.0 m flies parallel to the Earth's surface at a point where the downward
component of the Earth's magnetic field is 0.400 x
T. If the induced potential between wingtips is 0.900
V, what is the plane's speed?
a. 250 m/s
flohrn,/
~ ,
b. 338mls
emf =
d.
e.
-
417mls
569 mls
y= 6d.o-
Jg/v(
-2
A%
, g--
V-
=
OAT
a, 4~x1K / O-
~
SO
f;fd
,'
- I 1. An RL series circuit has: 5.0-mH coil, 1 .O-R resistor, 12-V battery, ammeter and switch. After the switch is
closed for a long t i ~ efind
, the final value of the current.
a. 2.5 A (b.
12A>
/
h h ' ~6 e ~ d r ~ c h *
c. 0.015 A
AT
d. 2 400 A
10
+&=O
Z = - d Lt z O , ok
- 12. What is the stored energy in a 0.50-mH coil canying a current of 4.0 A?
a. 2.0 x
J
c
c.
d.
e.
i
q
10-3 J
8.0 x
12x10-'J
16 x 10-'J
V = fL I
z
-- zL J 0 , x x & - 3 ~ , ( ~ ~
&00L/J-
147,/63J-
-
F
Short Answer
Please show your work in solving this problem.
13. At the Fermilab accelerator in Weston, Illinois, singly-charged ions with momentum 4.8 x 10-l6 kg.m/s are
held in a circular orbit of radius 1 km by an upward magnetic field. What B-field must be used to maintain the
ions in this orbit? (q,,, = I .6 x 10-l9 C)