94.20: A magnet is dropped through a vertical copk fsgr ,l28go5per pipe slightly larger than the magnet. Relative to the speed it would fall in air, the mgrf ol 5ks2,g8agnet in the pipe falls:

  01.30: Lenz's law concerning the direction of an induced cucji)y m*viq: xe m z/oz+daej9.9/p2 yrrent in a conductor by a ij eeozz2mm9vy+qc.x9 y/ / dap):ij*magnetic field could be a restatement of

  11.25: The product (3 Teslas) × (2 meters) × (4 meters/second) is equivalipp;6fhx(l v)ent to which one of the 6v(pip;) xhf l following?

  04.34: A square loop is placed in a uniform magnetic fieldkq :ce:gvnu4m( 6 :otd 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 loopt64onu:e m (d:v kg:qc 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 the page.b5b t8emu2, 0til6 g 0vmdp)m.eblc m) The wire experibet2u)mv tme g m00pl,6 c.i) dbl8mb5ences an induced charge separation as shown. Which way is the wire moving?

  00.20: A wire moves with a velocity 0.g-mic r1lde v through a magnetic field and experiences an induced charge separation as shown. What is the directie1glm.cdir- 0 on of the magnetic field?

  05.33: The figure below shows a bar moving to the right on two con i an+a:oe lc.pr-7sp*ducting rails. To make an induced current i in cn:*laa7+p ps. eor-ithe direction indicated, in what direction would the magnetic field be in the area contained within the conducting rails?

  00.10: When a wire moving through a magnetic field has a voltage inducen9qc6cth 90p-oh 3ijed between qhi6e p0hc n9c3jt -o9the wire’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 has constant velocity 0.30 hsrz,ep- 6w:novb-9 p 8 .9ovhbd+dfb m/s traveling through a uniform magnetidhp+, wb8 hzb. verp:ovobf-n9d s9-6 c field 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 oriented end-on so that its opening is perpendg f3r9xu;sdmbm:)d10 o xub4v icular 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 tim uxu91bd3:msxg; drvmf)0b o4e 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 diagramu +ccn):caiv0y s z, vs98ti)* 0rcxef (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 response to this changexsce i+rua9*y)v0ivscn) 8: ,0cfz ct?

  08.29: A strong bar magnet pr erk0*jmf; )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 t*k )f;0rjrmpe he magnet because of the induced current?

  09.37: For the figure shown, the varo p cv136sz/qciable 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 resistopq3/cvcs1 zo 6r in the right-hand circuit?

  10.39: A strong bar magnet is held qxu00 )rcmd(zd9a6 t- 2qskc bvery close to the opening of a solenoid as shownz6 -qxkcrtsb)dc(2 d qm0a0u9 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 solenoid and which magnetic pole does the “??” in the diagram represent?

  14.34: Two circular loops of resistive wire are placed next snq x08cklo.5to 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 5q. k 0lo8csnxlinearly 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 rkw,j md*;cf.b esistance 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 variabledpa- xh)tm1fa) 9;eum 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 lov5vik myl il4 (l(+o s-blcnlv9* 9ez2op sits in a plane perpendicular 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 de*zv+nl lvseil-5v9 lyb2 k(4mi clo 9(scribes the result of this field increase?

  16.47: Two small loops ilpzf h3wdg+no2-(.e0l4qcef21 ( w9v bxyvoof wire are located close to a wire with conventional current directed up the page. A scientist then moves the loops away f q1dxlzg o22el43nwwfoy0+h(- 9bv(c.pief vrom 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 acc8sf/cf+2.amlzs f9*y d - nnxross 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 resifc -fz/9 8xlsncfsa.+*yd m2nstors 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 cir(4cjx ;ne* icmcuit as shown. The maxmc e*4cnij( ;gnetic field 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 plane of the page is decreasing in taif1v 8rcwp 9m7-,mlw t-mus/ime. A constant emf ξ is produced for the square l89vpfl,w/ums t-m7c 1ir- wamoop 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 voltmeter’s reading?