94.20: A magnet is dropped through a vertical copper pipe slightly largs 3jifmyf28qkrxs 73m r u(y96er than the magnet. Relative to the speed it would fall in air, the magnet yrr fs6uk s2 9jmq73xy83if(min the pipe falls:

  01.30: Lenz's law conce;g4xpip+db ;ci0 gg6hrning the direction of an induced current in a conductor by a magnetic field could be a gc;x4igh 06 pbdgip+;restatement of

  11.25: The product (3 /xa-jo5y8s7k a0 cjzgTeslas) × (2 meters) × (4 meters/second) is equivalent to which one of the follojkxac -5 syz0aj/8go7wing?

  04.34: A square loop is placed in a uniform magnetic field perpendiculakaayiv9 e k -hh),mx99r to the plane of tey i-m,xa9akh9 9 )hkvhe loop as shown. The 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 through a magnetic field directed i* ivhs-spg ozq) 0,,o t8up)afrcn*h3nto the page. The wire experiences an i h3o,pr,ov uhfssqa pgt*z* )in 80)c-nduced charge separation as shown. Which way is the wire moving?

  00.20: A wire moves with a velocity v through a magnetic field and experiencefn891a y*vxqm s an induced charge separation as shown. What is * 9vnx8am qyf1the direction of the magnetic field?

  05.33: The figure below shows a bar mov5rg/ u,)ihw 9 arp.toning to the right on two conducting rails. To make an induced current i in the direction indicated, in what direction would the magna.g n w itur95,h)/proetic field be in the area contained within the conducting rails?

  00.10: When a wire moving through a magnetic field has mx81nh/4;yh zdd -n tra voltage induced between the wire’srmdtdn hhx- 81z 4n/;y 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 rod has constant velocity 0.30 m/s travelin4+x,pao 6d7hul *e z k.d6ougmg through a uniform magnetic field of 0.060 T. The rod, velocity, and magnetic field are all mutually perpendicular. What is the p4oxl66 ah*dd+oku m,gzuep 7 .otential difference induced across the rod’s length?

  04.42: A solenoid is oriented end-on so f m) aa z,.u)zdee (+kg87htlvo dac-0n2rc 0rthat its opening 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 resistance is added as shown. Assume that the magnetic field from the solenoid, shown coming out of the pl7gz0cozfr d8um.2tv lah0 rk+ )n),a-ce ad(eane 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 di e.b acm-cx+y5agram (which are assumed to be close to each other), the resistance of the left-hand circuit is slowly increased. In which direction does the ga -e5 y.cc+xbmalvanometer needle in the right-hand circuit move in response to this change?

  08.29: A strong bar magnet is held very clib 66m-tjz ;mlose to the opening of a solenoid as shown in the diagram. As the magnet is moved away from the solenoid at constanbz;tm-m ij 6l6t speed, what is the direction of conventional 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 variable resistance in the circui1otfp49sqm pn;8dw2zy n* d r/t 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 left-hand circuit and in what direction is the conventional current thm s 2owp8ddn*f4tp1r 9zn/q;yrough the resistor in the right-hand circuit?

  10.39: A strong bar magnet is held very close to the opening of a soleu(-+hm dl8 leenoid as shown in the diagram. As the magnet is moved to the luld lem8+e -h(eft 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 diagram represent?

  14.34: Two circular loops of resis)yyonruvy;hmkx v5 ;4zy;6e8d j-xj 7tive wire are placed next to each other as in the figure. The circular loop on the left is connected to a constant voltage source V. The resistadj)jyzvxv7yrm8 ;5 uoke; 6-y4;y nxhnce of this loop is increasing 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 resistance of the onqsjs+) o ;q81qknpk.uter 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 q9w. *ev4xn h)1 ewypccva,bu no6()n, the variable resistance of the 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 i wvrxgxyrd :9ja2119 in a plane perpendicular to a spatially uniform magnetic field pointing into the plane of the p9wvx 2yxrd 11gr9:aji age 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 of wire are located close too5v8wfrm;w x. a wire with conventional current w f.x;85rov wmdirected 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 is moving to the left across a set of frictio zvdn7y l ei 7ui6.vj:.lr0n+eh/5g vqnless 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 fl7vr nvnlidh 5+0ez 6vq./.je:7y giuollowing 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 passes through the wxcg 982bwv/wcircuit as shown. The magnetic field of the solenoid, directedwg9b8c / wx2vw 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 pa(lxs rs6yyy2e b;0e6f ez( o)age 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 identical light bulbs of resistance f()y 6zsr l(ybe ;o6e20exysa 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?