94.20: A magnet is dropped through a vertical copper pipe slightly larger than t(vv9t rr);jtm wpl 1gd/qvw 0(he magnet. Relative to the speed it would fall in air, the mag9 lr m((g pwv1qrw0vtvt )j;/dnet in the pipe falls:

  01.30: Lenz's law concerning the direction s 01bec.g ed)eof an induced current in a conductor by a magnetic field could be a restat eeb)1d.g ce0sement of

  11.25: The product (3 Teslas) × (2 meters) × (4 meters/secondd* vmrb+s* r(d) is equivalent to which one o*(+rrsd*bm vdf the following?

  04.34: A square loop is placed in a unifvdc9n odb tmihq5ne 6 -vz6k).c;va 4,orm 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 through an angle ,b4)nceav cdd56. mo9 nhtvz vk-i6q;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 fie8zgy 3os5kfx 0ld directed into the page. The wire expergk80xf5 o3syziences an induced charge separation as shown. Which way is the wire moving?

  00.20: A wire moves with a velocity vnw)um*6g.g1fsy-rekz 8 + vjo through a magnetic field and experiences an induced charge separation a v*js-.uw 6g8o+mg) rne1k yzfs shown. What is the direction of the magnetic field?

  05.33: The figure below shows auc*fr)gc k0 +n bar moving to the right on two conducting rails. To make an induced current i in the direction indicated, in what dire*f kcngc)+u r0ction 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 5uoktrl,gh,s,g/ i3blmo t3 4voltage induced between the wire’s end okit3,tml4obgl ,rgs3 5,u/hs, 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 copp md 6soido;x)i:vjq8 *er rod has constant velocity 0.30 m/s traveling through a uniform magnetic field of 0.0do*6;qm dx8ijosi :v)60 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 opening is perpendicular to obn9aijc6*q0 26qk 2;e jhnr*osay;u 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 plane of the page, decreases uniformly in time at the same rate for each cirran s*6ne9o bq 6o2yu0q;kcjah*j2; icuit. Rank the circuits for the brightness of the bulb labeled R1 from brightest to dimmest.

  07.34 For the solenoids shown in the diagram z7ula,f)qw bq:so *cg/h21gt(which are assumed to be close to each other), the resistance of the left-hand circuit is slowly increase7h q g*/ flwqc,oz1agbus:t)2d. 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 openinv-kz;j63 gi w00bngf pg 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 conventional current through the resistor shown and what is the direction of the force on the magnet because of the induced cur3kv6 0-gzwjf0p b;ign rent?

  09.37: For the figure shown, the variable resistance in the csii*a-gk,fy+w 7 (mu/ah,h djircuit 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 throsmf- h*y ,da7jhk+w/ii(,uagugh the resistor in the right-hand circuit?

  10.39: A strong bar magnet is held very close to the openi* v)u8tv2 e zbl;a;ngnng of a solenoid as shown in the diagram. As the magnet is moved to the left toward the solenoid, a conventiovne;nba uv tzl);g2*8nal 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 placed nesf*m; z7cnar3 7f zwm7xt 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 resistan7a ;7 mcwrz7fz fsn*m3ce 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 outox3a cr1yry302se) + usgs4mbzq 08xner 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 them)8jfrszaxl 6u7,om9* u c*nfty , /yk 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 loo;vztr pe0rna 1.i0f/x y9-tpbpjj ; 2jp sits in a plane perpendicular to a spatially uniform magnetic field pointing into the plane of the page as shown. The magnetic field strength steadily increases with time. Whi nft;9x epz.j 1 ;-a/jvbyrpir2p00j tch one of the following effects best describes the result of this field increase?

  16.47: Two small loops of wire are located close to a wire with conve6p i 2utbkmd0fq.cx 63ntional current directed up the page. A scientist then moves the loops away from the current as shown. What is the orientation of the conven6m6b .uc0txq3pd2fiktional current in each loop while this occurs?

  17.35: A metal bar is moving tod,dakr7 h*8zyb* 2ptw the left across a set of frictionless conducting rails tdyhr z7bp8,a** w2dkas 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 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 througrrqlb ;mh u*rs 8*fnw;5ve,6 x. .wajrh the circuit as shown. The magnetic field of the solenoid, direct . blq8;.*fnam; urj6sr*w xeh r5,vwred 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 directe+y jp.6t4wpbqe e0yl v q4v;,id into the 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 sqjip .vp 4wqbqltv,;4y0 +ey e6uare 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?