94.20: A magnet is dropped through a verticac+2+fb ikw 8c+ta62.8 lawcys b* mtlhl copper pipe slightly larger than the magnet. Relative to the speed it would fall in air, the magnet in the pipem bsct wb+ ifwh8.628+al+2ct l*yak c falls:

  01.30: Lenz's law concerning the direction of an induced current in sgg*0ti ,-9j/ dcfoeia conductor by a magnetic field could be a restatemenot9-g j,d0icgse*i/f t of

  11.25: The product (3 Teslas) × (2 meters) × (4 meters/s : w9qnqzj0ep6econd) is equivalent to which one of th j0n9 q6peqzw:e following?

  04.34: A square loop is placed in a uniform magnetic field perpendiculareb;f .wznl66w12g n9 (vg cos mdpeyw,8l )ht1 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 rotated through an antyv;ml9c(w pzdw1g e 6lse8. f6 g hnob1nw,2)gle 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 di7ray: . apsr; 2kvxb *xe:-iuzrected into the page. The wire experiences an induced charge separation as shown. Which way is the wirepk.b vazs * u:7rexry2x:ia;- moving?

  00.20: A wire moves with a velocity v through 6-h3c q6hyswg4v1(t 6 bokcjln63hzfa magnetic field and experiences an induced charge separation as shown. What is the direc1lgwv3 b6cnctsy6hof hh3j4(6z-kq 6 tion of the magnetic field?

  05.33: The figure below shows a bar moving2hzna 4)j/m y uwa))qa 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 th2z )hawq a)j/a)y nm4ue conducting rails?

  00.10: When a wire moving through a magnetic field has a volr7,x6pg*; ,hkkb.lpdd crl1 mtage induced between the wire’pd, pllh7rx.bgkc; * ,d1 krm6s 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 09).p; bwj9 fi rm2tkcn.30 m/s traveling through a uniform magnetic field of 0.060 T. The rod, velocity, and magnetic field are all mutually perpendicular. What isbwfnt9)2p rmjic.9;k the potential difference induced across the rod’s length?

  04.42: A solenoid is orientjnu2v;mz *zp(ed end-on so that its opening is perpendicular 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 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. nuzpzvjm2*; (

  07.34 For the solenoids shown in the diagram (which are assq(/r7utfc 7 i() eiioeumed to be close to each other), the resistance of the left-hand circuit is slowly increased. In which directii/7uf(c(rt7eio i ) eqon does the galvanometer needle in the right-hand circuit move in response to this change?

  08.29: A strong bar magn r4wk-j 5jy,rc,* symh.*hsbfet is held 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 shown and what is the direction of the force on the magnet because oys*h- rk*,fj4w,hb.j ry5 scmf the induced current?

  09.37: For the figure shown, the variable resistance in the circuit on b+i hy7poj2dx0l+k4c-x;bo e the left is increased at a constant rate. What is the direction of the magnetic field at tojoxb ++ xchl2 0i4;y -b7dkephe 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 solenoid as scoooc.x 25s0 xzly3bn) zt3ybhs21 + vhown in the os3cs2zo xb.3cz0 + 2lhy)y5nto bx 1vdiagram. 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 pole does the “??” in the diagram represent?

  14.34: Two circular loops of resistive wire arej xgl+dl 8 gnx b1,xxou*jfn0d/)z:+ f 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 chang0 :gjfx*x) dou /n l+dn+fzl,1 8xxbgjing, 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 vagbc 6 m,ex:q2jriable 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 vz b1-w hlzeqmlh1d3 3-ariable 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 loovuc-tu1 y y:m/p sits in a plane perpendicular to a spatially uniform magnetic field pointing into the plane of the- myutycu :1/v page as shown. The magnetic 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 wif9d-ef-l*m nv7ua- ;ys ez: c9r6rgu nre with conventional current directed up the page. A-dgncr9f 6s-f r;vleen u9:uy7a mz -* 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 frictionless cnfswfd/frqq( 62a;p/ onducting 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 correctlf/d;wsq p2qr6 /n ff(ay 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 pnvmk lwji pk/; 7wuu/yw+t-(7, -ulclasses through the circuit as shown. The magnetic field of the solenoid,u w/ul,p ij nt; lwk(/77vwk+-lumy-c 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 ts x-ux,ejr-w, h58pnphe plane 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 connxpxw,s u -,np -8ej5hrected to the corners through the center of the loop. What is the magnitude of the voltmeter’s reading?