94.20: A magnet is droppe; 9snu1;hf yqkd through a vertical copper pipe slightly larger than the khqn1;;yu9sf magnet. Relative to the speed it would fall in air, the magnet in the pipe falls:

  01.30: Lenz's law concerning the dirxu9s *;sv c 1sa)tj8ew/9eb b4u2bisaection of an induced current in a conductor by a magnetic field could be cua8b/v92w* j ) si;bb9 axesss41 ueta restatement of

  11.25: The product (3 Teslas) × (2 meters) × (4 m1dqd/o1:he ewz5 lud.iq; n;peters/second) is equivalent to which one of wl uhqdq/ :end.;;ie51 opz1d the following?

  04.34: A square loop is placed in a uniform vy1io qwn /oi 7li*-j,magnetic field perpendicular to the plane of the loop as shown. vnyoojiiq /i7*-w ,1lThe loop is 0.5 meters on a side and the 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 aop 1. 7,i-xoxoyu2regho t0m.ip*9z through a magnetic field directed into the page. The wire experiences an induced ch-.xoh,o 1p9.az 7mgyi*x0rtuo2opei arge separation as shown. Which way is the wire moving?

  00.20: A wire moves with a velocity v te vs12;xexg1zt uv; f5-r6tfyhrough a magnetic field and experiences a;tyr f1-fv szvux615g2ee;x t n induced charge separation as shown. What is the direction of the magnetic field?

  05.33: The figure below showk8l pbg5yj /w9s a bar moving to the right on two conducting rails. To make an induced current i in the direction indicated, in what direction would the magnetic field be ig9by j8p5/kwl n the area contained within the conducting rails?

  00.10: When a wire moving through +a(p)htzxqm) a magnetic field has a voltage induced between the wire’s ends, p( )qz+x atmh)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 cg 30xn z*9mj,,wsw 8b4(rolnync c5kpopper rod 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 difference indugxz 0mcnj9kyw ,*,b(crn 8w p5ol34nsced across the rod’s length?

  04.42: A solenoid is oriented end-on so that its op)1b4 cim rpn((ncn2ck ening is perpendicular to the circuit containing the two light bulbs as drawn in figure C1. For figures C2 and C3, a shorting wire of negligible resistai(r)1nbc n( ckpnm4c2nce 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 shoj/5a/yi2mma y0a3lqev .oi( q wn in the diagram (which are assumed to be close to each other), the resistance of the left-hand circuit is slowly increased. In which direction does the galvanometer needle in the 0.mi y/q2l aaemv ij/a5oy3(qright-hand circuit move in response to this change?

  08.29: A strong bar magnet is held f6wz7i rz18+ vgqkwd )very close to the opening of a solenoid as shown in the diagram. As the magnet is moved away from the solenoid at constant speed, what is the direction of convenk7fwqg1iz)w zd+68rv tional current through 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 va+kardj 22u) mjriable resistance in the circuit on the left is increased at a constant rate. What is the direction of the magnetic field at the point P at the center of the j2m r)a2+dkujleft-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 held very clos.v99tg 2 4v88r yschwypecp6b e 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 current in the solenoid and which magnetic pole does the “??” in the 4pvehtv bcc y99p.6ry28 g8 swdiagram represent?

  14.34: Two circular loops of resistive wire are placed next to,bmba xn0 yt1bbk 9m(m:lfjl+;8.z fr each 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 i.a8x: j zmb(; rly10+bblf , fnk9mmbtncreasing 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 vari h;4:(rxo- u(lqriw:pew0ww 3hc6xte able resistance 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 tl );hntvef(. k x)im8jb6win(r q eaz --wl4,lhe innercircuit $R_{inner}$ 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, conducting wire loop sits in a plane perpenmp.:fa(b/rrhqs*e slz w 2f4c4a; oo* dicular to a spatially uniform magnetic field pointing into the plane ofa4a2epoh :oc / mr *.; 4wzs(*fqbflrs the page as shown. The magnetic field strength steadily increases with time. Which one of the following effects best describes the result of this field increase?

  16.47: Two small loops rl* *)/plmv iaof wire are located close to a wire with conventional cur *pillv/a rm*)rent directed up the page. A scientist 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 is7j z3 q,e sl9-zyw2vfx moving to the left across a set of frictionless conducting rails as seen in the figure. Th97, s2wf j- lxz3yezvqroughout 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 relation between the magnitude of the currents through each resistor at the instant shown?

  08.50:. An infinitely long solenoid pa9tq )tyk5s- vpsses through the circuit as shown. The magnetic field of the sot y-pqsv tk9)5lenoid, 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 kg+(bd jfzio*,ka/t 4 of the page is decreasing in time. A constant emf ξ is produced for the square loop enclosing the field in the figure. The square loop has three identik(,4z+i *gfo jadtbk/cal light bulbs of resistance R in it and an ideal voltmeter connected to the corners through the center of the loop. What is the magnitude of the voltmeter’s reading?