94.20: A magnet is dropped througiy e;5i9idmo6k w)k4 th a vertical copper pipe slightly larger than the magnet. Relative to the speed it would fall in air, the magnetde i oim)k5it6y;4k w9 in the pipe falls:

  01.30: Lenz's law concerning the direction of an induced current in a conductoxgrfkbet-t 5sjz,3s 91,hgf- gz9ou /r by a magnetic field could be f-/ug- zsrftjz3ex1kgobh5,99,tgs a restatement of

  11.25: The product (3 Teslas) × (2 meters) × (4 meters/seunw;4 cs rn4f,ao 8,klcond) is equivalent to which one of t n,,wr4clo 8;sn4 ufkahe following?

  04.34: A square loop is placed in a uniform magnend/n) o d *m)+i)kotdge3. utotic field perpendicular to the plane of the loop as shown. The loop is 0.5 meters on a side and the magneto)dt3k *))nd.og tdoe iumn/ +ic 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 -kzp6 m :zqln4field directed into the page. The wire experiences an inducl:zn-4m kzq6ped charge separation as shown. Which way is the wire moving?

  00.20: A wire moves with a velocity v through a magnetic field and experience8isrsj3y pcx:0cm6( bs an induced charge separation as showjbi (csr 63:c yxs80pmn. What is the direction of the magnetic field?

  05.33: The figure below shows a barhj,4a jgg ;z 0bpode,468mq :kvxc;f k 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 conductinmq,;c4 0ovg h;e,6jdazb:g84 j xkfkpg rails?

  00.10: When a wire moving throug;27cz 16xb6gahormun h a magnetic field has a voltage induced between the wire’s ends, that v 1nxacb7uom6g 2;h6z roltage 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 d+vxq y-*e2yu constant velocity 0.30 m/s traveling through a uniform magnetic field of 0.060 T. The rod, velocity, and magnetic field are all mutually perpendiu-y2+*qvexd ycular. What is the potential difference induced across the rod’s length?

  04.42: A solenoid is oriented end-on so th282fslg l8gu(jj ydwt 98 qo+dat 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 jt l9od8gdjwfyul (2s2q+8 8gthe 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 show.pl1)uef0 lbdv t8sx6 n in the 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 the right-hand circuit move in responblufe xp. d s)l6v8t10se to this change?

  08.29: A strong bar magnet is held very closep- n4efxsh6 o-x0 3ijqc)0eyb 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 beca0 )yibn pho-f6e34exc qs0-j xuse of the induced current?

  09.37: For the figure sh iaw1i0 / u1msz,yhke8own, 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 an e0uih/k1,1wyai sm8 zd in what direction is the conventional current through the resistor in the right-hand circuit?

  10.39: A strong bar magnet is held ver u) wcoi/ea*9xw) .jary 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 cuaax/ w)9iu *e)o wc.rjrrent 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 are placed next to each o)qu ubqvbj :h;h bl;qae65i .-1)pujother 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 loop) and what is the orientation of the conventional current in the rig)j. ;:j p-6e1qbah q) buluovih; q5buht-hand loop (as viewed in the figure from above)?

  11.41: For the figure shown, the variable resistance of the (cf ri5rrkb32 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 variable resistance o;mka*t k::vom.5e je yf 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 sitsaih82a4vh .v2wq*w3 8n b)bobb*dc l w in a plane perpendicular to a spatially uniform magneoww* dc aqw2ib8a. 3bblv8h4 n2b*)vhtic 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 result of this field increase?

  16.47: Two small loops of wire are located close to a w;jikm,cu: ;:x wn 4vnnaya 2)eire with conventional current dunxaw nkm); n ve:i4y,:c2j;airected up the page. 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 ackceb77im00g(dkkxi ste (r05v 1f4tcross a set of frictionless conducting rails as seen in th 00k75v0 41 kitc(rd(xgtm7 cskebf eie 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 magnitude of the currents through each resistor at the instant shown?

  08.50:. An infinitely long solenoid passes through the ;:yd obkjfk9*3 8k 1ftsvwch9circuit as shown. The magnetic field of the solenoi wbt; *919ovykkffs3kh8cjd :d, 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 isz48xtu1 xtx o 6m1l8mj decreasing in time. A constant emf ξ is produced for the square loop enclosing the field in the figure l8u4x81ox z6 mmt1tjx. 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 reading?