Important! Physics 2220 Spring 2014 Paolo Gondolo PLEASE FILL IN THE INFORMATION BELOW. Name (printed): Name (signed): Student ID Number

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1 Physics 2220 Spring 2014 Paolo Gondolo EXAM 2 PLEASE FILL IN THE INFORMATION BELOW Name (printed): Name (signed): Student ID Number U Discussion Instructor: Anthony KC Matt Paul Peter Important! You are not required to answer all questions in this exam. You will receive points toward your exam points for every question correctly answered. Partial credit is available, however a minimum amount of work and explanation must be shown to receive any credit (for example, a mere list of equations with no explanation of their connection to the problem will not receive credit).

2 Physics 2220 Spring 2014 Paolo Gondolo Data: Use these constants (where it states, for example, 1 ft, the 1 is exact for significant figure purposes). 1 ft = 12 in (exact) 1 m = 3.28 ft 1 mile = 5280 ft (exact) 1 hour = 3600 sec = 60 min (exact) 1 day = 24 hr (exact) g earth = 9.80 m/s 2 = 32.2 ft/s 2 g moon = 1.67 m/s 2 = 5.48 ft/s 2 1 year = days 1 kg = slug 1 N = pound 1 horsepower = 550 ftpounds/s (exact) M earth = kg R earth = km M sun = kg R sun = m M moon = kg R moon = km G = Nm 2 /kg 2 k = Nm 2 /C 2 ε o = C 2 /(N m 2 ) e electron charge = C m electron = kg μ o = 4π 10-7 Tm/A (exact) N(Avogadro's No.) = atoms/gmmole = atoms/kgmole 1 Tesla = 10,000 gauss (exact) ρ(h 2 O) = 1000 kg/m 3 cos(a ± b) = cos a cos b a sin b sin(a ± b) = sin a cos b ± sin b m proton = kg h = J π = 3.14 c = m/s 3 1 x x a dx x a 3 dx x x a 3 a 2 x 2 a 2 ax 1 e dx e a ax xdx 1 3/ 2 x a x a xdx a x a x dx n x x a x a dx 1 a x a n x x a a x xdx x a x a dx 1x 1x sin, or cos a x a a dx 1 n a bx a bx b dx 1 2 a bx ba bx

3 Physics 2220 Fall 2009 Spring 2014 Paolo Gondolo Name: Unid: Discussion TA: Exam 2 1 Show all work!! Report all numbers to three (3) significant figures. Answer the following questions for the AC circuit on the right. (c) [10 pts.] What is the rms current through the 200 mh inductor? [10 pts.] What is the rms voltage across the 200 mh inductor? [10 pts.] To bring the circuit to resonance, should the frequency of the AC source be increased or decreased from the value indicated? Justify your answer.

4 Physics 2220 Fall 2009 Spring 2014 Paolo Gondolo Name: Unid: Discussion TA: Exam 2 2 Show all work!! Report all numbers to three (3) significant figures. The 10-turn loop of wire shown in the figure lies in a horizontal plane, parallel to a uniform horizontal magnetic field, and carries a 2.00 A current. The loop is free to rotate about a nonmagnetic axle through the center. A 50 g mass hangs from one edge of the loop. (c) [10 pts.] What is the magnitude of the magnetic dipole moment of the loop? [10 pts.] What magnetic field magnitude will prevent the loop from rotating about the axle? [10 pts.] For this to happen, should the current in the loop flow clockwise or counterclockwise (as viewed from above)? Explain your reasoning.

5 Physics Fall 2009 Spring 2014 Paolo Gondolo Name: Unid: Discussion TA: Exam 2 3 Show all work!! Report all numbers to three (3) significant figures. [10 pts.] What are the magnitude and direction of the magnetic field at the center of the loop in the figure, assuming the straight wires are very long?

6 Physics Fall 2009 Spring 2014 Paolo Gondolo Name: Unid: Discussion TA: Exam 2 4 Show all work!! Report all numbers to three (3) significant figures. A flexible circular loop 6.50 cm in diameter lies in a magnetic field with magnitude T, directed into the plane of the page as shown in the figure. The loop is pulled at the points indicated by the arrows, forming a loop of zero area in s. [10 pts.] Find the average induced emf in the circuit. [10 pts.] What is the direction of the current in the resistor R, from a to b or from b to a? Explain your reasoning.

7 Physics Fall 2009 Spring 2014 Paolo Gondolo Name: Unid: Discussion TA: Exam 2 5 Show all work!! Report all numbers to three (3) significant figures. A metal rod of length L = 50.0 cm is suspended from two springs of spring constant k = 100 N/m as in the figure. It is connected to a 12.0 V battery to form a circuit of total resistance R = 0.1 Ω. A uniform magnetic field B = 100 mt is directed horizontally perpendicularly to the rod (out of the page). After the switch is closed, the rod moves to a new equilibrium position. [10 pts.] In which direction does the rod move? Explain your reasoning. [10 pts.] By how much does the rod move?

8 Physics Fall 2009 Spring 2014 Paolo Gondolo Name: Unid: Discussion TA: Exam 2 6 Show all work!! Report all numbers to three (3) significant figures. A 400-turn solenoid of length 25.0 cm and radius 2.00 cm carries a current of 3.00 A. (c) [10 pts.] Find the magnetic field inside the solenoid. [10 pts.] Find the self-inductance of the solenoid. [10 pts.] Find the magnetic energy stored in the solenoid.

9 1'11\~ll~ 2220 "prin~ 2014 Paolo (,ondolo Name: Unid: Discussion T A: _. :P..:;..e-..;;..W..;;.. _ Exam2 1 Sbow all work!! Reoort all numbers to three (3) significant figures. Answer the following questions for the AC circuit on the right. 200mH (c) [10 pts.] What is the nns current through the 200 mh inductor? [10 pts.] What is the nns voltage across the 200 mh inductor? [10 pts.] To bring the circuit to resonance, should the frequency of the AC source be increased or decreased from the value indicated? Justify your answer. rrns = 10 V f =200Hz 4 0 ' 2.0 ' (a.) CRKS e~hs = ri(h$ = lt.l \Lw- -- I C.w \ :::: I I C2HS - '2.R f L - 2u:f(!. -\ C = C,+ ~:. 6~F = ~4.2 t'ha ===--- ~ {Jo) GUL.Ifei'IS = (C) f > fre.s

10 Name: --~--~--~~? Unid: 4...: /V_S _~_t ;y; l Discussion TA:...: --, Exam2 2 Show all work!! Belgrt all numbers to three (3) significant figures. The 10-tum loop of wire shown in the figure lies in a horizontal plane, parallel to a unifonn horizontal magnetic field, and carries a 2.00 A current. The loop is free to rotate about a nonmagnetic axle through the center. A 50 g mass hangs from one edge of the loop. 10 turns (c) {10 pts.] What is the magnitude of the magnetic dipole moment of the loop? [ 10 pts.] What magnetic field magnitude will prevent the loop from rotating about the axle? [10 pts.] For this to happen, should the current in the loop flow clockwise or counterclockwise (as viewed from above)? Explain your reasoning. N;; fo :!'= 2.. A : 0,00~... ~ ort-s'.... -'> b. -), -~=f:~~ :..,.,,. _.,.._ ) ) ;:: [o. ( A-VV~~J ( c. foe k...-r1 ~ 'F rof,.j...er;...,.m.. H.d v--ii/ alf)vr ~» J'lll<t 9'1-,~ltll~l /--ftey!!~ +o fj. w~ YPz_uJye._ a( t_f' 0.;,.. '>t!

11 Name: Unid: , Discussion TA: :...f~e~f.ll.-':::e;..:..r Exam2 3 Show all work!! ReQOrt an numbers to three (3) significant figures. [10 pts.} What are the magnitude and direction ofthe magnetic field at the center of the loop in the figure, assuming the straight wires are very long? 2.0cm 5.0A (1).-u.. (~ ) J_.L/littc. 21[-,.. ( '2.) (1)! r = J. o c.m.. ( (!)t/jv CPtilu~'tiW.>. ~-'- ~ fl"ml.,(.ai( ~ raiucma) rule.)

12 I'll\ 'll' 2~11 "'prill!! t Paolo (.ondolo Name: Unid: , Discussion TA: _;,_~fv1~,.._~j.-:!...f::l Exam2 4 Show all work!! Reoort all numbers to three (3) significant figures. \ A flexible circular loop 6.50 em in diameter lies in a magnetic field with magnitude T, directed into the plane of the page as shown in the figure. The loop is pulled at the points mdicated by the arrows, forming a loop Of zero area in S. x X X [10 pts.] Find the average induced emf in the circuit. { 10 pts.] What is the direction of the current in the resistor R, from a to b or from b to a? Explain your reasoning. X X R ~ - ~f J-t Atf ( X X -:. - -=.. ":1 -!l,_g[_,) ~~, I- A.J X ~~ ~~A $o fitc./oof :~ J~, ~t' H~ hta ch.~..,~, ",.., -f'ila.v..,'s. Ot.A:-l of -li.l. Pt>...je.,v A~,..dlvlJ ~ l.f'-"1; 1 5 Llf.NV.~ -~-~ ~,ut.u:-t--4 ~..(J.,, ~ 1 X

13 Name: --~~~ Unid: Discussion TA: _, _ Exam2 5 Show all work!! Reoort all numbers to three (3) significant figures. A metal rod of length L = 50.0 em is suspended from two springs of spring constant k = 100 N/m as in the figure. It is connected to a 12.0 V battery to form a circuit of total resistance R = 0.1 n. A uniform magnetic field B = 100 mt is directed horizontally perpendicularly to the rod (out of the page). After the switch is closed, the rod moves to a new equilibrium position. k [10 pts.] In which direction does the rod move? Explain your reasoning. {10 pts.] By how much does the rod move? ~ J fass-e.-, o~-o ~ r~~-~ ~c-ov.r~ ~-- oj--ocl B yot"""f-s. oc..~f- cf ~~ f~f<=- >) ~ :.ZJ:Ax VL& ).t:ix :: zl:. ~

14 l'h''il' 2211 "Prill!!, 2014 Paolo (,ondolo Name: Unid: -----:::: Exam2 Discussion TA: _._?_a~<..._j... ) 6 Show all work!! Reoort all numbers to three (3) significant figures. A 400-tum solenoid of length 25.0 em and radius 2.00 em carries a current of3.00 A. {10 pts.] Find the magnetic field inside the solenoid. {10 pts.] Find the self-inductance of the solenoid. (c) [10 pts.] Find the magnetic energy stored in the solenoid..r, -=- 2;, C) c~ r-=2,cjo c""' d 6", { -=- ( t 17 rf t ff(!)c)) { j) -=- DrO~()J T I! I - -::o ~oj-t] c) utl ~ b)g,-~-~-l ~ lwa ~-_;=-AI~ t~l J.~ =-)//r(lf J~ :::: ~o nai It ;rr ~ A/2, otr -:: -/~,.1r r T ;;IT-. )/~ --=-~ L. ::- ~~ < T ~kc>t~t+l ' (M-kr~~ ~~w7: L= r A/fa) I}~ { 1_)1-o I - r! Vw ut1-= ~") v~( ===- v..,-r :::: ~Aa t 1( r ~ (f~ u;;..t~~j~ == )4,1)... :r l I. I (A lk~fve~ v'-1., 1 [ Ij := i '.l'f