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Unformatted text preview: PIiY 2426: Engineering Physics 2 Exam 2H: l3 March, EllDE Name: LIE DU SSH: :2 i} (ll) (Last 4 Digits} ._. I) A small metal sphere of radius, r, = 20 mm, initially,r has a net electric charge, Q = 165 ME. A second larger metal sphere of radius, r: = Eﬂﬂ mm, initially:r has a no net electric charge [i.e. net charge of zero). The centers of
the two spheres are separated by a distance of d = lﬂﬂl) nun. rl=2ﬂ mm : exit} I“ % r3=200 rnrn : D n W. What are magnitude (11C) and s_igg (+f—} of the net electric charges on each sphere (q, and :11) respectively after [hey are then connected by a thin
conducting wire“? lCaution, use Si units. r J"
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x7 i941 ; 1'2 jL/ W lb) What is the tetal eurrent, IT , through internal resistance, r '? Hint, use Ohtn’s Law, I. = 8.me . t , L /
I : Flam ‘— 1: is] What is the terminal veltage, VT '5’ _
"I, _— t1“. —:r.t': 53’ : 5V 1d) What are the branch currents, II and I: ? Hint, note what the veltage is aeress
eaeh resistor, then applyr Olim‘s Law. j I __ : : 1l' : W _ : — _,]_ /
.I I   5,: ' .I' la) What is the pawar dissipated in all three resisters, P, , Pl , and P3 '? , _. r_ .3. i __ !
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tfi' "r 1: Fl : 1: 1—3 ": —_' r, —_ : :3 / 1%? 3a.) What is the equivalent resistance, Rah , ef the fellowmg network if all
resistere have the same value: R = 2!) KS7. ‘? r" 1
.3 T7, L'fLy/ 31:.) What is the equivalent capacitance, Cal, , of the following network if all
eepaeimrs have the same ‘value, (3 = 2 HF ‘2'
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“FtIre. W / M 4a) What is the capacitance, C = ?,of the following parallel plate capacitor, where
the plate separation is, d = 5 mm, and radius of plates is, R = 5E} mm, and
glass is between the plates {tt = 4.5)? Note, r‘trea of plates = rtR2 . Caution, use 31 units. _ TTTL
_— : Kt: #— : &.'2am"HF "" 3 4.13] Assume that there is no net charge (q=[l) initially on the parallel plate
capacitor. At time t={}, the switch (SW1) is closed and the parallel plate
capacitor begins to charge. When completely charged, what is the maximum charge qr,“ on the capacitor? .. W a ﬂlhhjwlf; C if _" [IEQyLGFH— : {:"?,5 3‘3"]— (3 : 3.15xlo'”¢ 4c] What then is the value of the electric ﬁeld, E in Wm, in the gap?J y /
_ i F . : iii"m 1 5i 3 fl “3 m 4.d) 1What is the work , in Joules [l], done by the battery to charge the capacitor to
a maximum charge qmm? Hint, this is the same as energy stored in capacitor. l} T .rfll'tr'___ Gaff3 .r of i : [y3_ Et’ at I503— ' W or _.. "1‘3 l a PD J 4.e] Which plate is positively charge¢@g'r Circle choice here.
... 1/ 4 5a} A parallel plate capacitcr cf plate area (A) and plate separaticn (d) is ﬁlled
With two dielectrics, K1 and K2 , of equal area (NE). Shcw the capacitance is given by
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R, as a ccpper wire 2.4 mm in diameter. hcth wires being the same length L“? Use 31 units! Hint, set RFE = RC“ , then preceed. E
Area = m2 ={ed1y4 '20
pa" = 1.69 x HIE $1111 a”
pa: = 9.36 x 10“: ﬂmJ
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This note was uploaded on 08/26/2008 for the course PHY 2425,2426 taught by Professor Ronald during the Spring '08 term at University of Texas at Austin.
 Spring '08
 Ronald

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