94.20: A magnet is dropped tkz f/j2mwx +5 d:zjvp3hrough a vertical copper pipe slightly larger than the magnet. Relative to the speed it w+:zfj2/kj5 pzxv 3mdwould fall in air, the magnet in the pipe falls:

  01.30: Lenz's law concerning the direction of an i nx fnz(.2gq)k/vbxc -nduced current in a conductor by a magnetic field could be a restatement o)v/gnxc k.-xbnq zf 2(f

  11.25: The product (3 Teslas) × (2 meters) × (4 meters/seri z sexs 7dp(8.b0uk1cond) is equivalent to which80(rpub kss i1dexz.7 one of the following?

  04.34: A square loop is placed in a uniform magnetic field perpendi t: qg po(7ridsv)bw v*d.96ibcular to the plane of the loop as shown. The loop is 0.5 meters on a side and the magnetic field B has a strst qvo.r7)i bd v*bi6(:pdg9wength 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 tyayrkobb/0t.(s -n(*c2 m- qyxtn w b4he page. The wire experiences an induced charge separation as shown. Which way is to c*nny-bm 0r4/ysbay2.(- wqb t(kx the wire moving?

  00.20: A wire moves with d4 oym/djx ,rvv)c-,xa velocity v through a magnetic field and experiences an induced charge separation as s)xvyr ,dcjx ov,4/m-d hown. What is the direction of the magnetic field?

  05.33: The figure below shows a bar moving to the right on two con5d vadu1m9 iki9a6 kj4ducting rails. To make an induced current i in the direction indicated, in what direction would the magnetic fj1m6vi uda ki99dk5 a4ield be in the area contained within the conducting rails?

  00.10: When a wire moving through a magnetic field has a voltage induced betw8b q0en16 ev:y2vpf (jqbuns.;1q xvdeen the wibpfsub2v6e.1 dq n10q(x8q ;vv: njyere’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 hag+ k8smt g:k1is constant velocity 0.30 m/s traveling through a uniform magnetic field of 0.060 T. The rod, velocity, ankgg1: t8+ imskd magnetic field are all mutually perpendicular. What is the potential difference induced across the rod’s length?

  04.42: A solenoid is ul9 n*wkx. 4rsn;0izq oriented end-on so that its opening is perpendicular to the circzl ;9 kxinr wn0*4s.quuit 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 assumed to be z 2qpt/7f8wmlcw y0*d close to each other), the resistance of the left-hand circuit is slowly inwl7 /2p*m fcwztyd8q 0creased. 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 cnlpdj 9h cbt19 u0t7qlyqi)2;lose 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 s;79)ctj1 p9ibh2ulq qy0tdln hown and what is the direction of the force on the magnet because of the induced current?

  09.37: For the figure shown, the variable resistlwck68a:+puzpq+:z i ance 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 direclkap:zp6:8w zcu+ q +ition is the conventional current through the resistor in the right-hand circuit?

  10.39: A strong bar magnet is heyz+9eo*5 sxxg1l *lj*b9lts3 4 tet cjld very close to 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 is the direction of the force on the bar magnet+3 *x cl *j1g4otzles9jxy*tl b9se t5 because of the induced current in the solenoid and which magnetic pole does the “??” in the diagram represent?

  14.34: Two circular loops of ren .s, 3ym3vhw c 2;d4tue)otxwsistive 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 x)m w.u;yocd3h ntw342v,set 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 ou 6-7j mw6 c*ymkmrvgq2ter 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 resistanc (kp3qidbdee /g .nk*)e 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 perpen)y llt +kv0+lpdicular 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 follop)kl0+lv +l tywing effects best describes the result of this field increase?

  16.47: Two small loops of wires ,6febym3p rlc8j7e 8 are located close to a wire with conventional current directed up the m8 rs, lcyb3je86pe7 fpage. A scientist then moves 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 to the left across a set of frictionlt0q3i7ok c o*sess 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 choices correctly indicates the direction of the conventional current in the resistors and the relation between the magnitui07oc *so3k qtde of the currents through each resistor at the instant shown?

  08.50:. An infinitely long solenoid passes through the circuit as shown. The6. xy +loi1i .d44jonhkkj/i h magnetic field of the solenoid, directed into6/ yjj 1+4xdo.kiinihok 4h.l 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 decreasin stxij.x4nd:pf4c* h :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 volt. i4ts:jxh:np* f4cxdmeter’s reading?