94.20: A magnet is dropped through a x3wgjd7vup6 vo ie +ci48/l;bvertical copper pipe slightly larger than the magnet. Relative to the speed it would fall in air, the magnet in the pipe falls/o3plcexdi u+ 6ji 4 gb7vv8w;:

  01.30: Lenz's law conw to.1 ysw/ea) ojwt;4cerning the direction of an induced current in a conductor by a magnetic field eto t.o/;ajw4s) y1wwcould be a restatement of

  11.25: The product (3 Teslas) × (2 mbe*o4chmm f(:dolf67cyx ) i0eters) × (4 meters/second) is equivalent to fbic0d7xyo(4)lecm mf h 6 *o:which one of the following?

  04.34: A square loop is placed in a uniform magnetic field perpendicular t2zvzi:4a l sh4o the plane of the loop as shown. The loop is 0.5 meters on a side and th lh42iv z4sza:e magnetic field B has a strength of 2 T. If the loop is rotated through an angle of $90^{\circ}$ in 0.1 second what would be the average (RMS) induced EMF in the loop?

  97.32: A wire moves through a magnetic field directed into the page. The *ofjh: s*zydubs4,8p wire experiences an induced ch d8pshs, *:ojbzf uy*4arge separation as shown. Which way is the wire moving?

  00.20: A wire moves with a velocity v through a magnetic fie 6)t uebmf3kd4ld and experiences an induced charge separation as shown. What is the direction o e6mtf4d3k)buf the magnetic field?

  05.33: The figure below shows a bar moving to the right on two conductw4m ywszb /2(n7ff 3vbt;ui 6iing rails. To make an induced current i in thwmb /bn4fui; 3zvyfw 7(s 62ite direction indicated, in what direction would the magnetic field be in the area contained within the conducting rails?

  00.10: When a wire moving through a magnetic field has a voltage induced betw40a7e2dn j5 t lkqt s,leiw2d6een ttl7q n2ik aed 26sjl etw45,d0he wire’s ends, that voltage is
I. directly proportional to the strength of the magnetic field
II. directly proportional to the velocity of the wire
III. directly proportional to the diameter of the wire

  95.30: A 0.20 m long copper g * 3 e3( 55jweg3r mpdwzbl;vcl-fws0rod has constant velocity 0.30 m/s traveling through a uniform magnetic field of 0.060 T. The rod, velocity, and magnetic field are all mutually perpendicular. What is the potential v5dzmbj;wl0sf-g3ge c533l*e w(pw r difference induced across the rod’s length?

  04.42: A solenoid is oriented end-on so that its omc(oy.y wj--i pening is perpendicular to the .(cmi- o-yjywcircuit containing the two light bulbs as drawn in figure C1. For figures C2 and C3, a shorting wire of negligible resistance is added as shown. Assume that the magnetic field from the solenoid, shown coming out of the plane of the page, decreases uniformly in time at the same rate for each circuit. Rank the circuits for the brightness of the bulb labeled R1 from brightest to dimmest.

  07.34 For the solenoids shown in the diagram (which arethm;i 3u uldg49k5ry2x7)xs t assumed to be close to each other), the resistance of the left-hand circuit is slowly increased. In which dirtyt 7mghusk d5; )2943lxirx uection does the galvanometer needle in the right-hand circuit move in response to this change?

  08.29: A strong bar magnet is held very close to the opening of a solenoid a7v wl: zezx/4 juv1ly;5 wgv0os shown in the diagram. As the magnet is moved away from the solenoid at constant speed, what is the direction of conventional current thz0wjv4g7 vvel5wyx;z:1u/ o lrough the resistor shown and what is the direction of the force on the magnet because of the induced current?

  09.37: For the figure shown, the vatctgts0se ilmsk;z+ -/ g69 t3riable resistance in the circuit on the left is increased zt0;e ktsss im +-gclt93/6tgat a constant rate. What is the direction of the magnetic field at the point P at the center of the left-hand circuit and in what direction is the conventional current through the resistor in the right-hand circuit?

  10.39: A strong bar magnet is heldlgs ;mj;1-.gl bc bv+c very close to the opening of a solenoid as shown in the diagram. As the magnet is moved to the left toward the solenoid, a conventional current through the resistor shown is directed from A to B. What is the direction of the force on the bar magnet because of the induced cur lgvlcb.mj;cb +-;1gsrent in the solenoid and which magnetic pole does the “??” in the diagram represent?

  14.34: Two circular loops of resistive wire are placed next to e6/m ,rr: n cpqcnsi7y2ach other as in the figure. The circular loop on the left is connected to a constant voltage source V. The resistance of this loop is increasir6n ,m2 7/qp isccny:rng linearly with time. As the resistance is changing, what is the direction of the magnetic field at point P (the center of the left-hand loop) and what is the orientation of the conventional current in the right-hand loop (as viewed in the figure from above)?

  11.41: For the figure shown, the variable eudjntwr2 5:c)2(l yyresistance of the outer circuit $R_{inner}$ is decreasing at a constant rate. While this is occurring, in which direction is the magnetic field associated with the outer circuit at the point P in the plane of the circuit and in which direction is the conventional current through the resistor $R_{outer}$ in the smaller interior circuit? The two circuits lie on a flat table.

  13.35: For the figure shown, the variable resistance of the innercirgu 912v5a wcpwcuit $R_{inner}$ is increasing at a constant rate. While this isoccurring, in which direction is the magnetic field associated with the inner circuit at the point P in the plane of the circuitand in which direction is the flow of electrons through the resistor labeled $R_{outer}$?

  12.38: A square, conducti.q rpwbo2 2ws fvjogi *c-o(4-ng wire loop sits in a plane perpendicular to a spatially uniform magnetic field pointing into the plane of the page as shown. The magnetic field strength steadily increases with time. Which one of the following effects best describes the result orwq gv .oj2fwo2c-ps(-*b i4of this field increase?

  16.47: Two small loops of wire are located close to a wire with conventionju; ;hajbb:i pb +;f1zal current directed up the page. A j;b fzipb ;;u:hja +b1scientist then moves the loops away from the current as shown. What is the orientation of the conventional current in each loop while this occurs?

  17.35: A metal bar is moving to the left across a set oxr o.6ls +v*lv h-ufgb0 q:q,rf frictionless conducting rails as seen in the figure. Throughout the region between the rails, there is a uniform magnetic field directed into the plane of the page. The resistors labeled X and Y are identical. Which one of the following choices correctly indicates the direction of the conventional current in the resistors and the reqrbx:ufvq rv*s -lgo6+,0l .h lation between the magnitude of the currents through each resistor at the instant shown?

  08.50:. An infinitely long so7 ac+bl57ve1 q1hnxlo)rld*fk5 s4op lenoid passes through the circuit as shown. The magnetic field of the so7e cl 71l proa4+)qlxvhs fon5 15b*dklenoid, directed into the
plane of the page, is weakening which produces a constant emf of magnitude ξ for a closed loop around the outside of the solenoid. Once equilibrium is established in this circuit, what is the voltage across the switch S?

  15.50 A magnetic field directed into the plane of the page is decreasv , km/qkyne* a;cm7d5ing in time. A constant emf ξ is produced for the square loop enclosing the field in the figure. The square loop has three identical light bulbs of resistance R in it and an ideal voltmeter ca qm5env7yk* ,/cd m;konnected to the corners through the center of the loop. What is the magnitude of the voltmeter’s reading?