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Unformatted text preview: Physics 222 ABC EXAM #3 (Chapters 2832) FALL 2008 Name: . Instructions: For the appropriate problems circle the letter corresponding to the correct answer. If you are sure that no correct
answer is showmyou should write your answer in space (0 ~ ~ . Some questions require ﬁlling the blanks. ‘ Note ‘
that some problems/questions have more than one (I) correct answer. For those problems/questions you should give all the
correct answers. The numbers in the [ 1 represent the points for the problem. [14.] 1. Matching: Write the number of the items on the right in the space in front of the correct answers on the left. ( 2,) The 2 component of the electron’s spin magnetic dipole moment 1. Q (C) electric charge
(5") Bohr magneton 2. S. = m,h/2n, m, = (+/~)( 1/2)
( 7) In a massspring system, the spring constant k (N/m) 3. L (H), inductance
corresponds to .
(3 ) In a massspring system, M (kg) corresponds to 4. I...“ z = nth/21:, m; = 0, +/l, +/2, +/m¢ ma)
( ‘ ) In a massspring system, v (in/s) corresponds to 5. p, = eh/41cm ‘
( i ) In a massspring system, x (m) corresponds to 6. i (A) current
( I] ) The 2 component of the electron’s orbital angular momentum 7. l/C (F)", Capacitance [6] 2. A fully charged ideal capacitor is connected in parallel with an ideal inductor using wires that have some resistance. The
circuit now begins to oscillate. Circle each of the true statements below? (Note that there is more than one true statement.)
Answers: (a) For the circuit the inductive reactance will always cancel out the capacitive reactanoe to giVe resonance.»
(b) This is an example of an undamped oscillator. It is possrble to keep the oscillations going indeﬁnitely by'insezting an
alternating emf source that has the right voltage amp do and frequency, in series with the capacitor and inductor.
Energy will be lost during each cy of the oscillations and the oscillations will eventually step. (e) The oscillations will
ntinue indeﬁnitely (i.e, for ever). is is an example of a damped oscillator. For the RLC circuitat the right R = 56.7 mi), C = 0.82 an L = 475 pH, and £(t) = 13.8V sin [21:04.3 MHz)t]. Use
this information to answer problems 3, 4, 5 and 6. [8] 3. Determine the re r: g e of the capacitor in the circuit ! R L
Answer: (a). 5.40 mg. @3 13.6 mﬂ. (c). 22.5 m. (d). 49.0 :2. c 1 (e). 67.0 min. (f) at)
[8] 4. The impedance in the circuit is
AnSWer: (a) 13.7 m. (b) 33.7 mi). @617 mﬂ. (d) 73.7 mi). (e) 93.7 m. (f)
[8] 5. Determine the phase ugle to complete the following statement:
. , "" ":21; ’ ; t“... 51:31 is given hyie’ ) sis; mAsin l21r(ii.3»MHz)t. ¢]. . a ,. u   . . e
Allbhcr.”.1.. (n) 30.0‘ (c) 55.0“ (d) 57.6 “. (e) 8&4". (t) __ .
[5] 6. Whi of the phasor diagrams below would best describe the current and voltage relationships of the circuit in problem 3?
Answers: " (iii) VR 5 (iv) VR
VL t (0d i 6
’7 a.
VG Vc VL that condition?
Answer: (a) (i). [10) 8. The magnetic ﬁeld through the threequ circular loop
changes according to the relation Rt) = (790  5.20?) uT, where t is in seconds.
The resistance of the loop is 8.40 Inn. What is the magnitude and . direction (circle the correct choice) of the current that is induced in the loop at t = 3.0 seconds? (The radius r of the loop is 3.80 cm.)
Answer: (a) 72AM. (b) 59.5 uA. (c) 32.4 m. (d) 28.4 11A. (e 12.6 MA. (f) __ . Direction: CW or w erpz‘ ..‘....,;.i.i _. _ > For Problems 14 & 15 use the information below: Physics 222 EXAM #3 SPRING 2007 A Name: . [8] 9. Four of the following equations are known as the Maxwell‘s equations. Circl each of those four equations. [Bods=,uo(i +id)m. (b) IE0 = daft“) .‘ (c) Hzeq‘x—‘gtﬂ. ’IBodA=O.
(e) id=lk£o(¢g) @IEIdA= Eods= Mi“). [1 l] 10. Match the equations given in problem 9 with the statements below by writing the letter of the equation in the space by the correct statement(s).  Statements: Q This is a ﬁctitious current (i.e., as the current between the lates of a capacitor). 4 Suggests that electric chargescan be of two types having the same magnitude of charge. Gauss's Law for electrostati . ’
Farraday’s Law. A changing magnetic ﬁeld produces an electric ﬁeld an A changing electric ﬁeld pro uces a magnetic ﬁeld. Suggests that isolated electric charges can be found in nature. suggests that there is a connection between ' t and'electrtc and magnetic ﬁelds. __Q_\_. AmpereMaxwell's Law. Gauss's Law for magnetism. Predicts that no isolated magnetic monopoles exist in nature. [6] 11. A 7.20 mg resistor and 5.80 uH'inductor are connected in series across an ideal
battery that supplies 9.0 V. How much energy is stored in the magnetic ﬁeld of the inductor when L the magnetic ﬁeld beco es stable? + l . )
Answer: (a) 1.00 J. @453 J. (e) 9.60 J. (1) a (c) 5.50 J. (d) 7.62 J.
[8] 12. Two identical shaped pieces of wire are placed as shown in the ﬁgure. 1, = if 4.5 A and i, and bare in opposite directions. If the magnitude
of the magnetic ﬁeld at P due to only i, is B, (T), the
magnitude of the net magnetic ﬁeld at P due / to i, and l, is Answer: (a)0(T). @ZB. (T). (c) 0.5B1 (T). (d) 4.581 (T). (e) B,/4.5 (T). ‘ (t) An induced current will be set up in the conducting loop. The direction of the magnetic ﬁeld at P
the center of the circle, due t this 'nduced curre t is Answer: (at) There is no magnetic ﬁeld at P. (b) To the leﬁ. (c) To the right
' ‘ , (e) Perpendicularly o: t of the was. . a".
_;...,gs.., Three concentric current carrying cylindrical conductors A, B and C, pass through the paper. The direction of each current is indicated by O or x.
I}. = 14.0A, i3 = 17.0 A and lc= 24.0 A. [5] 14. The net current (magnitude and direction) through the cross section
shown is Answer:l.0 A. (b) 34.0 A. (c) 19.0 A. (a) 10.0 A. (e) 3.00 A. (1) . Directiﬁ W“ 1k; M
[10] 15. Determine the magnetic ﬁeld (magnitude and direction) at a di gee of 5.00 cm from the center of the cylinders.
Answer: (a) 96.0 u’l‘. (b) 34.0 in“. (c) 72.0 1.1T. (a) 46.0 “T. 28.0 pr. (1) Direction: Ccn/ [12] 16. Six particles are moving when they suddenly enter a magnetic * "
ﬁeld B. The lines represent the paths of the particles in the magnetic ﬁeld. . . . . .
Match the path number with the charge or lack of charge on the particle.
(Use + for positive,  for negative, or n for neutral ) 1 n , 2.  3. n 4. + , l 5. "' 6 ‘4' L} ...
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 Spring '11
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