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Unformatted text preview: JAN-28-2004 28:38 erik P.01/01 University of Toronto ECE 159s - Electrical Fundamentals January 29th 2004 Last Name: First Name: Student Number: Quiz 1 — C0u10mb’s Law, Electric Field, Electrical Potential, Capacitance
(e = 1.6x10‘19 C, eo=8.85x10‘12 CZ/Nmz) Question I [5 marks] Four point charges are located at the comers of a square, shown in the diagram below.
[-1C at (0,0), (2,0) and +1 C at (l, -1),(1,1)] y (m) x (m) (1,1) P‘ a) 2 Marks — Find the Total Electric ﬁeld experienced on an arbitrary point on the dotted
line shown in the above diagram. (For —1 m < y < l m) msgcck-Im we SE‘E, M 41, MAC F'G‘C‘ no x—Cﬂ-PQMnt E: J— ( 1c 3‘_ it; + -—lCﬁ ME) r ..‘c Me)
4115” . (l *3? (ll—3y f 3" [+31
(am A3 Am: 53 alum-I clutch] E; J, ,1. _ _L_ _ __L’._"Lf ): r250 [ 2(\+:z)1/,*(i+3)l(t~3)z]
4‘16» "*3" “13" (“5’ 4m anrmtugb’e b) 3 Marks - If we place a test charge, QC, at an arbitrary point (except y = 0) on the dotted
line it will start an oscillatory motion. If we initially place a test charge of QC = 10 “C
and mass, mo = 10'3 Kg at (l, 1N2), what will its velocity be when it passes the point
(1,0). [Hint Calculate the potential difference between the points (1, 1N2) and (1,0)] ﬂuke V(°0):O w rtﬁwcwt V(l,-'-)=J_ 1C 4, 1C -1: _ 1c ~ .
ﬂ 4na,( ) (4 2453—) 1-; a 1+3 mi «a:
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9w. Gauge i» W'Wn‘it.’ chef” is At): QCLVUJLVUAQL 2%“ (4-433) Bwt we khnw Tim-1 AK: mJVZ:-AU L
v : 4% (242;) = to if; 12,.o4m/
mane, . mass 5 lof2 "TOTAL P101 JAN-28-2004 28:33 erik P.01/01 University of Toronto ECE 1598 - Electrical Fundamentals January 29th 2004 Question 2 [5 marks] The capacitor depicted is constructed out of tWO metal plates as follows: width W, length
L, plate separation d, and ﬁlled with a material with dielectric constant K. Q‘CV a) 2 Marks - The capacitor is charged up so that a charge Q; is present on the top plate and -Q0 is present on the bottom plate. What is the voltage difference, V0, between the two plates in
terms of the physical measurements and Q0? CE: = emu“. _VO:QO_ 04 4 A Z 2,th b) 3 Marks — The capacitor is disconnected from the source so that it is not allowed to
discharge, ie Q0 remains constant. The dielectric material is then pulled a distance x out of the
space between the plates, as shown below, so that now the area of the dielectric remaining
between the plates is W(L-x). Calculate the new voltage on the plates by considering the
situation as two parallel capacitors. Note: Assign air a dielectric constant of l. V: Q0 : Q0
' at, (.44.; , 3
AH? 20f2 TOTAL P . 01 ...
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This test prep was uploaded on 04/18/2008 for the course ENGINEERIN ece159 taught by Professor B.wang during the Winter '08 term at University of Toronto.
- Winter '08