94.20: A magnet is dropped througt gzjw n 7efovcr,a+j0:-g7a5h a vertical copper pipe slightly larger than the magnet. Relative to the speed it would fall in air, the ma5,77 oc0ae gvz aj rjf:wgtn-+gnet in the pipe falls:

  01.30: Lenz's law co*z07a20r wkfqu 1ihmj ef p2a2ncerning the direction of an induced current in a conductor by a magnetic field could*fzfua21hqj im kra ep20w7 20 be a restatement of

  11.25: The product (3 Teslas) × (2 meters) × (466-7ac )rm di7sjmphe meters/second) is equivalent to which onp a)6- c mm7hdires67je of the following?

  04.34: A square loop is placed in a uniformb 845v:ygv: ixshg)row //xijalqq09 magnetic field perpendicular to the plane of the loop as shown. The loop is 0.5 meters on a side anx v:jwx0/glo4g9a8his):/irv5yq b qd 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 thad 4*t,eaki -ax36xtr rough a magnetic field directed into the page. The wire experiences an induced charge separation as shown. Whic etxk 4-rx3ti*aada6,h way is the wire moving?

  00.20: A wire moves with a velocity v through a magnetic fieldlt(ya tos 0()fuq( +y+cfptn, and experiences a(++fyapuy, oqn ((tt)cfsl0 t n induced charge separation as shown. What is the direction of the magnetic field?

  05.33: The figure below shows a bar moving to the right on twourv x9 ,h 092bdleks3u conducting rails. To make an induced current i in the direction 9s ev 09uluh,3 dbxk2r 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 between( p r1het5srm:x+h5rf the wire’s emfh+ e5 :1rt5rprx(hsnds, 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/si,wm s +i;yhzv8kno30*bqu 7 wji e-j4 traveling through a uniform magnetic field of 0.060 T. The rod, velocity, and magnetic fbiwh,*o-u iqvy37i ; 0 jw8j+4mzksneield are all mutually perpendicular. What is the potential difference induced across the rod’s length?

  04.42: A solenoid is oriented end-onj7 4+ pkibcbj7 so that 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 th b+kj4c7pijb7 e 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 assume7d ; rvhs3kxzhz91 0svjr15uo d to be close to each other), the resistance v7 h310svk51r;rhx ds9uozj zof 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 aid0nd+yy vnv xf 41,*mbx g4f,be-k. l etvw45 solenoid as shown in the diagram. As the magnet is moved away from the solenoid at constant speed, what is the direction of conventional c vvy,te-l b1efign 4,v5m4 wyk 0d fxnxdb.*4+urrent 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 circuihwmh0 3x m;u :jds-b1nt on the left is increased at a constant rate. What is the directio n3mx u-bm;w10jhd:hsn 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 opening of a svuz ontpjr1p; 9.0-kgolenoid as shown in the diagram. As the magnet is moved to the left toward the solenoid, a conventional current through the k;vr- 19 pu.jpog0nztresistor 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 resistiwpu ) 4kjaabsw)palcz );5 4(gve 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 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 w4cj)g5 wz;au)akp4b (l ap)sin the right-hand loop (as viewed in the figure from above)?

  11.41: For the figure shown, the variable resistant k9+;oin,ktr7)fyt b ce 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 va jtkwk+;(s;s:s c bnr,riable 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 in a plane perpendi2 ezlzt(+xny*/l,qci cular to a spatially uniform magnetic field pointing into the zl+, (2nzl/x*cteiyqplane 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 increase?

  16.47: Two small loops of wire are lzhkglg5 upbj(u qv*qt/ 8(4+bocated close to a wire with conventional current directed up the page. A scientist then moves the loops away from the current asb(pgl uv thb+ /ug*j 4k5qq8(z 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 se9:f6fs5iwh vyt 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 following6vf ys: hw59if 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 ll fb8q42fw ll0ong solenoid passes through the circuit as shown. The magnetic field of the solenoid, directed inwfbl 2l40f8lqto 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 intq3h mk))c z; tbuyn4c(h9pk0ho the plane of the page is decreasing in time. A constant emf ξ is pruc)n h)y;hp4kzmh c9k0b( tq3oduced 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 connected to the corners through the center of the loop. What is the magnitude of the voltmeter’s reading?