94.20: A magnet is dropped throughik(/ g fonmc8,/ gkax8 a vertical copper pipe slightly larger than the magnet. Relative to the speed it would fall in air, t a/mc8xo,f( 8/ gnkgikhe magnet in the pipe falls:

  01.30: Lenz's law concerning the direction of an induced current in a conductorulu+2p*jnk jwz+imd*3zt f(5 by a magnetic field p+wj m zi jf+*kd2t5z( ul3*un could be a restatement of

  11.25: The product (3 Teslas) × (2 meters) × ,*ft 5vtcdb:ld do.( 8vsho:x (4 meters/second) is equivalent to which one of the folld.f(tbvx:h d:5,c*8odovsl t owing?

  04.34: A square loop is placed in a unifqc3ut+k7r 8c vg z*bqx35kt7form magnetic field perpendicular to the pl7vr*+ kqbf7c8kt 35uxc3z tqgane 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 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 wiv3hr4;, fnzcfp.pj +mmau x/w pxi0(4re experiencei.4mm43;(a x 0cvnfz jp,+/fp uphrxws an induced charge separation as shown. Which way is the wire moving?

  00.20: A wire moves with a velocity v through a magnetic field and exper3.u8l6u /*,e: aejdcaqa in gziences an induced charge separation as shown. What is the direction of the m 36:qezg j*audieua n.,c/a8lagnetic field?

  05.33: The figure below shows a bar moving to the right onksq)tt -,1hxhg+ j 1htk6vs wo*d 4r.n two conducting rails. To+6 1nhw sj4 k1g)t-oshkt,r.*vq thxd make an induced current i in the direction indicated, in what direction would the magnetic field be in the area contained within the conducting rails?

  00.10: When a wire moving through3 ss+ w3(fuy7cci69llao, sqr a magnetic field has a voltage induced between the wire’s ends, that voltagewqsu3i7c,+yrass6l9c 3lo f ( 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 hapoa2 b)-kmi39 p5 zeuzs constant 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 potential difference induced across theoup 2-3ikmzp9 z5a) eb rod’s length?

  04.42: A solenoid is oriented end-on so that its opening is perpendicul a9(y bjeleofj2/(/:t szxuv) ar 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 e/ufe(jt(j vb sy :a9zx2/lo)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 r v9/d3kpu. ./owv)jkgrar db;f*zf9close to each other), the resistance of the leffguvdawr/zv k o .)r*bkdrj./p 9f;9 3t-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 openi21* ksog5tfnqytdw o;one55 4ng 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 becae4w1gqy;t55no d o5 2k*tns ofuse of the induced current?

  09.37: For the figure sh/ksg*q80l zgp6xjguz3p k- 6o own, the variable resistance 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 through the resistor in the rightlkz6o/3qu gj0 s8 -g *xgk6pzp-hand circuit?

  10.39: A strong bar magnet is held very close wzixb,zpy),m -n2 u(d8gze,kto the opening of a solenoid as shown in the diagram. As the magnet is moved to the left toward the solenoid, a conventional current through the resistor shown is directed from A to B. What de,nz8i(w2um,kg) yx ,-bp zzis 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 p3;pq ds)osnc-tan b;9laced 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 l;c;n-3n)a d qb po9stsoop) 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 variabyg-5q(1rnzv3zoeq8+ zh 6jcpf,s r5hle 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 the innercircuit 0 vvs,evtj:m;w* 49b* setusg $R_{inner}$ 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 a1yw (b1ie:y3ku gezk7 plane perpendicular to a spatially uniform magnetic field pointing into the plane of the page as shown. The 3egy k:kuyw 7(1b eiz1magnetic 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 to a wi7)mj93vu1zn a1leoed re with conventional current directed up the page. A scientist then mzvne1 a el3)9odu7j1moves 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 t-oyv9o) up-ef o the left across a set of frictionless conducting rails as seen in the figure. Throughouy-fo )euv-op9t 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 through the circuit as shown. Thts*hzm3cn: b8e/f hw9e magnetic field of theshz8h3cb/ :tnw 9*fem 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 of the 8;.xdimlhlc dfa1c8)*u(qia page is decreasing in time. A constant emf ξ is produced for the square loop enclosing the fie ;ilf 8 )lxm(8qa*dc 1hudaci.ld 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?