94.20: A magnet is drooimj; i6ep;/d pped through a vertical copper pipe slightly larger than the magnet. Relative to the speed it would fall in air, io e6 /;pjdim;the magnet in the pipe falls:

  01.30: Lenz's law concerning the direction cwu5zee ew8bj1;/ ofedi-x ,0 of an induced current in a conductor by a magn ,o-exbecf8e/ w; zedu5i 1w0jetic field could be a restatement of

  11.25: The product (3 Teslas) × (2 meters) × (4 meters/second) is equiva u om(bi-:4qbylent to which one of the fol4(m:by ioqb u-lowing?

  04.34: A square loop is placed vfw4/qtv8 yy9ota, ; hin a 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 rotated through4yft/w8q v ot y9,a;hv 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 wir zpf6bx l.(j:ae experiences an induced charge separation as shown. Which way isz.l:fa 6pb( xj the wire moving?

  00.20: A wire moves with a velocity v through a magnetic field and experiences k 57tfb p)nl-uan induced charge separation as shown. What is thu 7nfpb5 )klt-e direction of the magnetic field?

  05.33: The figure below shows a bar moving to the right on two conducting ra9j8ogmz8 pc y, x7p6qails. To make an induced current i in the direction indicated, in what direction would the magnetic field be in the area contained within the conducting railsp 8y, co zqg87px9ajm6?

  00.10: When a wire moving through a cb1t 0e0d .osxccnv)jln-b75magnetic field has a voltage induced between the -cetc.joxl05n0bd) cb 7nsv 1 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 constf f1gt1noz7 ozzhz8;i-e3h 4fant 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 ofefh 1hn 47-z 3g8oz1tzzi;fpotential difference induced across the rod’s length?

  04.42: A solenoid is or//+ ofijm /qrfiented end-on so that its opening is perpendicular to the circuit containing the two light bulbs as drawn in figure C1. For figures C2 andmf +//jf /oqir 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 (which2dofz,)9 f u 8mvtttd*dqy.p 51j lrv4 are assumed to be close to each other), the resivd4trd )mf j19v5 ,o2 ltd qt*fp8y.uzstance 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 solenoid)*mogkox 5ma--porfnt.o - 2g as shown in the diagram. As the magnet is moved away from the solenoid at constant speed, what ia -t 2xoo -frn.*5g p-kgm)ooms 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 shot-7lofk) ax2iwn, the variable resistance in the circuit on the left is increased at a constant rate. What x l2-fta7)koiis 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 held very close to the openj,,ug 8e;2vhs.v xb9x c) ulrqing of a solenoid as shown in the diagram. As the magnet is moved to the left toward the solenoid, a conventional cujleq rv u s2h;,).9vxg,ub8xc rrent 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 placed next to each othz62moc;sy1yq uxm5 c1 w9;fu eer as in the figure. The circular loop on the left is connected to a constant voltage source V. The resistance of this loop is increasing linearly with time. As the resistance is changing, what is the direction of the magnetic f6q 9;x1uc51u 2 y; yzemmoswcfield 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 resistan,neu rq7/ ojv2ce 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 innercircuit 5ozvrg )zvzk96m *3xp $R_{inner}$ 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 planxv:9htrdv7 9o7euic p it.-6z e 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 of this field inch6ri:i9pzvt79v x7uc .e-tod rease?

  16.47: Two small loops of wire are located close to a w0x1 e:nvmf.e9efh 4(l9errd(fx6 mrn ire with conventional current directed up the page. A scientist then moves the loops away from the current as shown. What is the orientation of the conventional curren1.rm9xlh(r09x dvr f:nfn4 fe(em6 eet in each loop while this occurs?

  17.35: A metal bar is moving to the left across aj*6 x);gacset set of 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 choicec6)at jx ;*gess 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 circuit as sg)cn q) nz1skye 6,v6o6wh0t (qbfp3ihown. The maqkoq)b3e61i w g6py 0s(, cf hntv6n)zgnetic field of the 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 the plane /k2rh.r*-hubxxt bx6 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 bu-b.r hrx6tb /xhk*u2 xlbs 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?