94.20: A magnet is dropped through a vertical copper pipe slightly larger t )quv /n,dolem3du5u*e2x0athan the magnet. Relative to the speed it would fall in v/2l utu3 qeen*0d)m5aud, xoair, the magnet in the pipe falls:

  01.30: Lenz's law concerning the direction8pmc j. 43bzs q8qdg:n of an induced current in a conductor by a magnetic field cou b:4 sgcjdm.qq pn8z83ld be a restatement of

  11.25: The product (3 Teslas) × (2 meters) × (4 meters/second) is equdi,hj u( d;u (li3elkmqkv.,8ivalent to which oq m . v8hlkkljuid,; d(ue3,i(ne of the following?

  04.34: A square loop is placed in a uniform magnetic 4*qf0 ie; jws)dsw 9h2idv k/hfield 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 rotatkew*s;q04 shj id/ 9ivd w)2hfed 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 wire.k*gyvwqfe3 )-snr/-m4,nzlcdg (j h experiences an induced charge separation as shown. Which way is the wire moving? *gy(/mnf4-z),ldce .nqgr 3wk h-vj s

  00.20: A wire moves with a velocity v k p3r6fc:/ypv)f/ w hzb.ig2 fthrough a magnetic field and experiences an induced charg:p / hg fkfrzb3ic) /f2.6vpywe separation as shown. What is the direction of the magnetic field?

  05.33: The figure below shows a bar moving to the rhg6 s;w:bdo9b8 (+a i7q3ai ghimqiiabsr8( /ight 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(ii8a hqrgbmihga39s+q w(/ i da 8b7:is6ob; contained within the conducting rails?

  00.10: When a wire moving t yn ek3yvtzyf8g8mq l o*p-/h4f;73jrhrough a magnetic field has a voltage induced between the wire’s ends, that volh8 vep4 myq 3;7fzkyl-o83yr fgt/j*ntage 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 x1.ms* pf i.0mt/3gkq;giwau copper rod has constant velocity 0.30 m/s traveling through a uniform magnetic field of 0.060 T.t 3x.p0iuqsmf.ak 1 mgiw;*/ g 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 r53l bi(amcv8 -k ciz8the 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 cb 8vcma3 k5i8r-zl(ilabeled R1 from brightest to dimmest.

  07.34 For the solenoids shown in th9l7t; 8pqn)dxv9chr je diagram (which are assumed to be close to each other), the resistance of the left-hand circuit is slowly increased. In which direction does the galvanometer needle in the9q jrx 7;c8 v)tdph9ln right-hand circuit move in response to this change?

  08.29: A strong bar magnet is held very s;o b-paxmj vy*u4l -.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 resist -uvo.;-xbjm*al4psy or shown and what is the direction of the force on the magnet because of the induced current?

  09.37: For the figure shownh u8, 9z 2w m.jxj+lhmce vph1jwqn2+z 9a:y2c, 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 i. n cl+ j ymzj22huh+veqw28pw9:m1ja,zcxh 9n the right-hand circuit?

  10.39: A strong bar magne vq 6gehqjtle4c f ox+684 76d*dhr1 hsgz-v)ft is held 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 forc-q zgqxj1v vhh6hds7 4e4g*rofe+ t86)l 6dfc e 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 ajd7h 0io uth6wga.+/ fre 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 directi0+h6.7gh/tfjiu waodon 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 outerok.sf :d uca.3 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 variabtc)gxo1i vfas: b)5t3rp; 2dzo )pp;we8tuq2le 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 sitn3x 1nylt0t 6xs in a plane perpendicular to a spatially uniform magnetic field pointing into the plane of the page as shown. The magnetic field strength steadily i3nl6n1t0 xyt xncreases 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 wire with7wa *.ietb9 u: llj n0xi-oof+ conventional current directed up the page. A scientist then moves the loops al.fl9b+w:ox 0j u- ao7*iiet nway 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 lefr**rfwcn3w/ / 1aumkgt 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 resc/k/3gra wm r*ufw n*1istors 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-r f9et*.zyuu long solenoid passes through the circuit as shown. The magnetic fie .rtfue u-*zy9ld 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 plansjd(vc-)e s g,e of the page is decreasing 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 voltmvesd- gj)c(,seter connected to the corners through the center of the loop. What is the magnitude of the voltmeter’s reading?