94.20: A magnet is dropped through a vcufx4k1o.o5dmli+7+a 47t- yblk. ck;m glzm ertical copper pipe slightly larger than t-im.g+out71c7bdm4k ;yl4k+x cl. fk5a molzhe magnet. Relative to the speed it would fall in air, the magnet in the pipe falls:

  01.30: Lenz's law concerning the direction of an induc:7 mtn3uev- ih5wds4t ed current in a conductor by a magnetic field :is-3 e ttdu5 m4hwn7v could be a restatement of

  11.25: The product (3 Teslas) × (2 meters) × (4 me ta/j2ioizf 1r dr.a2-ters/second) is equivalent to which onaijr /da. 1zr ito2f-2e of the following?

  04.34: A square loop is placed in a evs5k c,( d6zzfmet+ : bxc8n;uniform magnetic field perpendicular to the plane of the 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 rotzt+e c5mk( en b x;8:fzv6d,scated 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 direc6:f nj-,dmsjwted into the page. The wire exped6j:,ws- jf mnriences an induced charge separation as shown. Which way is the wire moving?

  00.20: A wire moves with a velocity /q+fimz:/ ljxp,qho 9v through a magnetic field and experiences an inducqql zi/o+9j :pmxhf, /ed charge separation as shown. What is the direction of the magnetic field?

  05.33: The figure belowb i7+7-0qt u1eusly )ngobac; shows 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 in the area contained within the conductinci07s;g+ulb1ntbu yea )-qo 7g rails?

  00.10: When a wire moving through a magnetic field has a voltage induced e54v3,:dk bvi.k kwxa between theb4 x :a, vwk3v.5dikke 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 rod has constant velocity 0 3:eh rdtq0z6s.30 m/s traveling through a uniform magnetic field of 0.0600 :z sd63thrqe T. The rod, velocity, and magnetic field are all mutually perpendicular. What is the potential difference induced across the rod’s length?

  04.42: A solenoid is oriented end-on so that its opening8(am 4 q3r s*car9cyys is perpendicular to the circuit containing the two light bulbs as drawn in figure C1. For figures C2 and C3, a shorting wiras4 ayy m8sccr3q*(9re 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 are assumed to be close xkvr fusq40;i-l(bmh9d7gn ;jh38 ulto each otlln 4 rhv9xuibkdu s;3 -7q ;gjf08(mhher), the resistance of the left-hand circuit is slowly increased. In which direction 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 ns/s2fp,txov -h 1o)8uy:u kt solenoid as shown in the diagram. As the magnet is moved away from the solenoid at constant speed, what is the direction of conventional current through the resistor shown and what is the direction of the-us8ko/2)p: 1xnt s,h vtfouy force on the magnet because of the induced current?

  09.37: For the figure shown, the variable resistanci (wf522ce1y cymp x9ij ,dn3de 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 left-hand circuit and in what direction is the conventional current tyn5ef12c2 ,im 39id xcd(wpy jhrough the resistor in the right-hand circuit?

  10.39: A strong bar magnet is held very /lpsg mk)s1a)baz5a* close to the opening of a solenoid as shown in the diagram. As the magnet is mo/alb)a5 )g pzksa m1s*ved 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 diagram represent?

  14.34: Two circular loops of resistive wire are pll8nph ;kg( 3hb (t(kygjz/xd4 aced next to each other as in the figure. The circular loop on the left is connected to a constant voltage source V. Th/dnlhzghgk3; p(k4 8b xy(jt (e resistance 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,nytcx5ik 2.oeckf d;b);i*1i the variable 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 thdkp vu+8-/g:kfi/q ife 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 perpendibit hqpdp,,w 3;8lg8 tcular 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 respb,ld ,th3 i8q 8tpw;gult of this field increase?

  16.47: Two small loops of wire are locatu,1i ad9 njg:/x fwxz a pe4i3a/5hsd4ed close to a wire with conventional current directed up the page. A scientist then move4 /ianughxj w3 1 d:e5dp,as/9axfiz4 s 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 op1)c/. stgejof 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 corre/p gc so.1tj)ectly 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 lol- q.q94 e 3askkb*jp5xgynp*ng solenoid passes through the circuit as shown. The magnetic field of tksy*nk xa9b* e-4q3j. pgqpl5he solenoid, 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 theqw1oh5 6p3r jf3d uewo/65ua dftq/,s plane 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 identical light bulbs of resistance R if5o qsd3jud61/tf 5weu36 ra / p,qhown it and an ideal voltmeter connected to the corners through the center of the loop. What is the magnitude of the voltmeter’s reading?