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Unformatted text preview: Questions (5 points each)
Please answer each questions by blackening the letter of the best answer. Q1 A power line carries current to the South. An electron 10 cm above the wire is traveling to the North. What is the direction of the force on the electron? 5 ,  a) To the East e) To the West l/ (9 j; b) To the North i) To the South ____,____———?—~ c) Straight up a Straight down I u/ ‘23 E d) Zero 7 ‘9‘”
A) é—T? 5 Q2 The circuit shown includes three identical A V’W’V light bulbs, a battery, and a switch. All circuit
elements may be considered ideal. Initially, it is
operating with the switch open. When the switch
is closed, which of t he following changes will occur? a) Bulb A will get dimmer . Bulb A will get brighter c) Bulb A will stay the same d) There is not enough information to tell Problems (30 points each). Please show your work and circle your
answers. Missing or incorrect reasoning will earn no credit. A 7' \
P1 Six ideal resistors and an ideal battery are 359 M \
connected as shown in the ﬁgure. I
a) Find the current through the 35 Q resistor. 30 V 10 9
b) Find the current through the 10 Q resistor. 20 Q
c) Find the power dissipated in the 50 Q resistor. /
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: 1/25“ w :55? P2 For a long period of time the switch S is in position
“b”. At t — O s the switch S is moved from position “b” to position a After a long time, the switch is returned to
position “b. ” Please ﬁnd each of the following. a) The current through the 1 M9 resistor just after the
switch moves to position “a. ” b) The current through the 1 M9 resistor at t = 5 s. c) The charge on the capacitor just before the switch is returned to position “b.” d) The current through the 1 M9 resistor 10 seconds after the switch is returned to position “b.” a? U/Uéé’lflbcreﬂ C 54:21!) To Tfﬁﬂdl C/ﬂCUI/ § 7‘7 I
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If ‘r P3 A very long copper wire of radius 5 mm carries a current of 200 A. The current density is
uniform across the diameter of the wire. 4', 5mm / , 5 ___._._——————— /—————9
Please determine L‘ a) The magnetic ﬁeld a distance 3 cm from the axis of the wire. b) The magnetic ﬁeld a distance 2 mm from the axis of the wire. c) The voltage drop across a 1.5 meter length of the wire. The resistivity of copper is“ ,\
1.72 x 10‘8 92m 69 (9&7? (05 P4 A coil is wrapped with 149 turns of wire on the perimeter
of a square frame of sides 23 cm. Each turn has the same area, B ®
equal to that of the frame, and the total resistance of the coil is
4.93 £2. A uniform magnetic ﬁeld is turned on perpendiCular to
the plane of the coil as shown. The ﬁeld changes linearly from 23 cm :3 L
0 to a ﬁnal value of 1.35 Tin a time of 1.19 s.
5,4 A t Please answer each of the following questions. a) What direction will current ﬂow around the square?
b) What is the ﬂux through the square after the ﬁeld reaches full strength?
c) What is the magnitude of the induced emf in the coil while the ﬁeld is changing? (a) 5 pure Wvémpwm/ﬂcy 77wqu 5 (pr/7&F Are;
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 Spring '10
 Dr.AndyGavrin
 Heat

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