Physics 102. Final Examination. Spring Semester ( ) P M. Fundamental constants. n = 10P

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Garey Murphy
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1 ε µ0 N mp M G T Kuwit University hysics Deprtment hysics 0 Finl Exmintin Spring Semester (0-0) My, 0 Time: 5:00 M :00 M Nme.Student N Sectin N nstructrs: Drs. bdelkrim, frsheh, Dvis, Kkj, Ljk, Mrfi, ichler, khshni,, zi & Shrm k πε ο N.m Fundmentl cnstnts / (ulmb cnstnt) / (N m ) (ermittivity f free spce) - π 0 T.m/ (ermebility f free spce) -9 e.0 0 (Elementry unit f chrge).0 0 (vgdr s g 9.8 m/s (ccelertin number) due t grvity) - me 9. 0 kg (Electrn mss) -. 0 kg (rtn mss) refixes f units - m 0 k 0 - µ n 0 p Fr use by nstructrs nly rb Ttl Mrks Ques. 5 8 Ttl Mrks

2 UT. Slve the fllwing prblems. Shw yur slutins in detil.. Tw identicl pint chrges Q Q +5.0 μ re held.0 cm prt lng the -xis, s shwn. Find the mgnitude f the electric field t pint. [5 pints] y E E k Q ( 0.0) k Q ( 0.05) E E x y E E + E N N. 0 N N ( + ). 0 N E E x E y.0 cm.0 cm Q Q x. int chrge Q is plced t the center f sphere with rdius. The electric flux thrugh the surfce re S f size is. Find the vlue f chrge Q. [ pints] S φsph φsph π ( 5) 55.5 Nm S Q Q 5.0 n ε O Q

3 . n the figure shwn nd the tw pint chrges re identicl nd Q.0 μ. Hw much wrk is required t bring chrge frm pint t pint B? [ pints] kq V kq VB W q V V ( V V ).5mJ B Q / B / Q. The cpcitrs in this circuit re given s, nd, nd the chrge n cpcitr is Q 0 μ. f the spce between the pltes f cpcitr is filled with dielectric mteril ( ), wht will be its new chrge? [5 ints] µ F + Q ε 5V ' µ F ' ' µ F ' + ' ' Q ε 90µ ε

4 5. The tw cylindricl wires in the figure re mde f the sme mteril, hve the sme length nd their crss sectin res re relted ccrding t. f the pwer utput f the bttery is 00 W, wht is the pwer dissiptin in wire? [5 ints] W l l , + + ρ ρ. The cpcitr is initilly chrged t Q 0 μ. The switch S is clsed t time t 0 s. Wht is the current thrugh the 0 kω resistr 0. s fter switch S is clsed? [5 ints] q t q q s k µ µ τ τ ) / exp( 0.0 Ω + Wire Wire 0 kω 0 kω 0 µf S

5 . The wire in the figure crries current nd is inside unifrm mgnetic field tht is perpendiculr t the -plne. f the -cmpnent f the mgnetic frce n this wire is, find the mgnitude nd directin f the mgnetic field. [ ints] B is utwrd F LB sin (90) B. 5T. 8. very lng wire crrying current is shwn belw. Find the mgnitude nd directin f the mgnetic field t pint, where. [ pints] B due t the hrizntl segment is zer B due t the verticl segment is B µ 0 T π Directin: int the pge 5

6 9. cylindricl cnductr with rdius crries current. The current is unifrmly distributed ver the crss sectinl re f the cnductr. Use the mpere s lw t clculte the mgnitude f the mgnetic field, fr frm the xis f the cylinder. [ pints] B dl πrb µ µ O B π µ π r enc πr T 0. slenid with rdius hs lps per meter nd crries current in the directin shwn. The xis f the slenid is perpendiculr t the surfce f squre lp f side nd resistnce. The current f the slenid vries with time s, where t is in secnd nd in mpere. Find the mgnitude nd directin f the induced current in the squre lp t. [5 pints] L φ π B π µ n ε ε dφb dt ( t s).8 µ V ε. µ π µ n ( 0.t + 0.5t ) ( t) L Directin : lckwise

7 T : nceptul Questins (ech crries pint). Tick the best nswer:. Electric field t pint is zer. t cn be cncluded tht ) there must be n chrges in the spce surrunding pint b) there cn be chrges in the spce surrunding pint c) electric ptentil must be zer t pint d) electric ptentil must hve negtive vlue t pint. sitive nd negtive chrges f equl mgnitude Q lie lng the xis f cylinder nd their distnces frm the nerest bse re equl. The flux thrugh the bse clse t the -Q chrge is ) psitive b) negtive c) zer d) nt enugh infrmtin t decide. +Q -Q. prtn is relesed frm rest in unifrm electric field. s it mves, its electric ptentil energy ) increses b) decreses c) remins the sme d) becmes zer. cpcitr with very lrge cpcitnce is cnnected in series with nther cpcitr with very smll cpcitnce. The equivlent cpcitnce f the cmbintin is ) slightly greter thn b) slightly less thn c) slightly greter thn d) slightly less thn.

8 5. circuit cnsists f three identicl lmps cnnected t bttery s shwn. The switch is initilly pen. Wht hppens t the brightness f lmp B when the switch S is clsed? ) t increses. b) t decreses smewht. c) t drps t zer. d) t des nt chnge. ε B S. lng stright wire crrying current nd psitively chrged prticle with velcity prllel t the wire re shwn. The mgnetic frce cting n the prticle is ) upwrd b) dwnwrd c) t the left d) zer. v. urrents, nd crried by three wires surrunded by the clsed lp re shwn belw. The vlue f the line integrl rund lp is prprtinl t ) b) c) d) dl 8. The figure shws lng stright wire crrying current nd rectngulr lp, bth in the plne f the pper. The current is decresing with time. The current induced in the lp is ) upwrd in segment b) dwnwrd in segment c) t the left in segment d) t the left in segment. 8

PH2200 Practice Exam I Summer 2003

PH2200 Practice Exam I Summer 2003 PH00 Prctice Exm I Summer 003 INSTRUCTIONS. Write yur nme nd student identifictin number n the nswer sheet.. Plese cver yur nswer sheet t ll times. 3. This is clsed bk exm. Yu my use the PH00 frmul sheet