94.20: A magnet is dropped through 6fddsv 3l 92 d:x-vkzfa vertical copper pipe slightly larger than the magnet. Relative to the speed it would fall in air, the magnet in dvsdv f3-zl9:6x2 kd fthe pipe falls:

  01.30: Lenz's law concerning the direc dt6.ouk0ja9ltion of an induced current in a conductor bjltuoka6d9 0.y a magnetic field could be a restatement of

  11.25: The product (3 Teslas) × (2 meters) × (4 meters/ezt /i2ueyvv( dl nvk 1p(r9,6second) is equivalent to which one of the followii1vzdyt,( 9r/ uv2ee6k(nlpv ng?

  04.34: A square loop ; wv0sa(osaf1is placed in a uniform magnetic field perpendicular to the plane of the loop as shown. The lf;v ao (0swa1soop 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 i4/l4s f-;sfjh jw8on wnto the page. The wire experiences an shnl4 j-4/ of w8fws;jinduced charge separation as shown. Which way is the wire moving?

  00.20: A wire moves with0hlg2 ofd4;rz zj fp28 a velocity v through a magnetic field and experiences an induced charge ;2jd4o fg hp0fz 28rzlseparation as shown. What is the direction of the magnetic field?

  05.33: The figure below shows a bar moving to the ri*zcx,i abp,tmo 3+zi)ght 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 ti)+im a3bxo ,p* ztcz,he conducting rails?

  00.10: When a wire moving throughfk gzl,-y p(5r a magnetic field has a voltage induced between the wire’s ends, that voltpyzglrf-k (5 ,age 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 thro4p 2ucugc(d r5ugh a uniform magnetic field4(u5rucp2gdc of 0.060 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 qnv2f9n ,xnb3 oriented end-on so that its opening is perpendicular to the circuit conb2f q3nn, xnv9taining 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 assumg exlwpxt 7h 3es-a-i e4up3m8 ukj/:)ed to be close to each other), the resistance ofp g 4luew jte3-uxi) p: 78-/eah3xmks the left-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 heg09lerc e/n* eld very close to the opening of a solenoid as shown in the diagram. As the magnet elec*ng /9re 0is 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 current?

  09.37: For the figure shown, thkdh*a bnn3+meq )7ze5 e variable resistance in the circuit on the left is increased at a constantne3 z 7aqb)hme*dn 5k+ 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 right-hand circuit?

  10.39: A strong bar magnet is held very close to the opening of a solen:1n 1:cq p a8x/ujzzdloid 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 solenoxln1jcz a 8:z:du1/qpid and which magnetic pole does the “??” in the diagram represent?

  14.34: Two circular l(ewp gzyzqy2 5n .sx-gx)avu :6s y(9koops of resistive wire are placed next to each other as in the figure. The circular loop on the le6 es9q kz.(-pn2x(yy:vy u a5gwxgsz) ft 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 viewed in the figure from above)?

  11.41: For the figure shown, the variable resistance of the outcxse1d v(v *i.bl; (vx*zegv8er 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 theo41 swwwe k0he*ew-1 v 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 perpendi 0xsuadlsu64k5df5ut 25qxq. cular 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 following effects best describes the resu655u4ut5x0duxqs.k f q l2ds alt of this field increase?

  16.47: Two small loops of wire are located close to a wire with conventional cumz ) kb0mai/fw;jahobcd1 r )cs(6 -:prrent directed up the page. A scientist then moves the loops away from the current as shown. What is the orientatmhib6sd /k )f1zb- )c opw;rma: 0c(jaion of the conventional current in each loop while this occurs?

  17.35: A metal bar is moving to the left across a set of frictiok 55vh(ewom b8u0kl4 cnless 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 ab8oml c 4(05vwhuekk5 re 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. The g9qr5v 9b2y/; g gd2v loje((3 alt6cinyo1nw magnetic field of the solenoid, directed lj 53qe t2na629yivovcgy9lo g; rg(nw(1/bd 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 plangds)-s 1epxe xw3 7,iqe 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 voltmeter s 1e,q7gdpxis3)wx-e connected to the corners through the center of the loop. What is the magnitude of the voltmeter’s reading?