94.20: A magnet is dropped through a vertical copper pipe slightly larg( o1hl d2xxpjyimlm(,0gwjd3 u1c0j1 er than the magnet. Relativej( uiw0 0pl 2l , 3gd1xjmyjc1d1ohm(x to the speed it would fall in air, the magnet in the pipe falls:

  01.30: Lenz's law concerning th((;0oubxsikz. e fic (e direction of an induced current in a conductor by a magnetic field could be a restateb (.oi sz(u;(xe0 ickfment of

  11.25: The product (3 Teslas) × (2 meters) × (4 meters/:mykitkwjsz,5bhs5 o ec -*0-second) is equivalent to which oc -mwyhbie,05kks *so 5t-jz: ne of the following?

  04.34: A square loop is plak/ s- /s o*qjaxs4ipu7ced in a uniform magnetic field perpendicular to the plane of the loop as shown. The loop is 0.5 s/u-7xsop*k q sja4 /imeters 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 dm sqaub .gh9a66 c.)bcirected into the page. The wire experiences an induc6qa..a 69g m cb)bcuhsed charge separation as shown. Which way is the wire moving?

  00.20: A wire moves with a velocity v through a magnetic field and experieaj28lo dg x+65dwo:ru ncrc1y/ i 6/krnces an i8ykox rd:/2/5 a i6c+wl1cu ojrrndg6nduced charge separation as shown. What is the direction of the magnetic field?

  05.33: The figure beld,6pzzq6jh. b5iuefa md(, ;p ow 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 conductipf pjddi q56a;hmbz, 6e,(u z.ng rails?

  00.10: When a wire moving through a magnetic field has a volt)pk8j8yh df4 :pwla 3oage induced between the wire 8d)4kpf8yhj pl3oaw: ’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 0.30 m/s traveling thro kx):dkgh;c tgq3 )jlg ad:+0-gxzjn/ugh a uniform magnetic field of 0.060 T. The rod, velocity, and magnetic field are all mutually perpendicular. Whatlt0d khcx; ) :qz+ kjxn)g:g- dj/3gag is the potential difference induced across the rod’s length?

  04.42: A solenoid is oriented end-on so that its opening r2t8sov g)j-gis perpendicular to thej2 o)8 vrgtsg- 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 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 assuoa.m4.h,d sdi9 l) qt+nz,nd7teb*ismed to be close to each other), the resistance of the left-hand circuit is slowly increased. In which direction does the galvanometer needle in the right-hand circui7m4l b+tso,a9qdte dz ,)n*..i sdniht move in response to this change?

  08.29: A strong bar magnet is held7zys pc *tz)z/ very close to the opening 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 )tzs/p*zc y7z 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 thg vph1 .g.d7fkt+f;khe 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 circui f1 hhtfvdgkp ;+7..kgt 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 (clwi8h) jdb69c xj/ mzrq2t (owkv(4solenoid 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 is the direction of the force on the bar magnet because of the induced current in the solenoid and which magnetic polxv(tc92jmiljz)( /8wdk6o (qcwbhr4 e does the “??” in the diagram represent?

  14.34: Two circular loops of resistive wire are placed next to each other at:oz 5 rcv(pg0s 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 in the right-hand loop (as viewe5ov r:0tgz(pcd in the figure from above)?

  11.41: For the figure shown, the variable resistance of the our) n/o,zv:(johnkao1 ter 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 inn e/a fmvs nw n.+c4 0t(vs7pkjuy 3tnzf:g8a88ercircuit $R_{inner}$ 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 perpendicular to a sp1k arpl.ex e)8xp;ho.atially uniform magnetic field pointing into the plane of the page as shown. The magnetic field saxk. eo)rh l;p8p.xe1trength steadily increases with time. Which one of the following effects best describes the result of this field increase?

  16.47: Two small loops of8*oecwr/igoo , z t0(x wire are located close to a wire with conventional current directed up the page. A scientist then moves the loops away from the current as shown. What is the w,goozoi 0 (e*/ cx8trorientation of the conventional current in each loop while this occurs?

  17.35: A metal bar is moving to the l* )gpqo/.rce2m)vz oceft across a 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 e/q2 * cmv )o)rgp.cozX 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 sol4iyvxo54 s1ex 2h8uyz9o -cuuenoid passes through the circuit as shown. The magnetic fieldx2ivz4ocxys5y4o9u -uh 81 u e 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 of the page is decreasingimz .m1ucvo4r:0ig+g 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 in it and an ideal voltmeter connected to the corners through the center of the loop. What is the magnitude of the voltmeter’s regi+:o.0r vcgzmmiu 1 4ading?