94.20: A magnet is droppedyhc3n lok p+h(bi+9qozn:h x9yw8.*d through a vertical copper pipe slightly larger than the magnet. Rela.+ihhnyqxb*8c:d o h(np k9z3 ow+9lytive to the speed it would fall in air, the magnet in the pipe falls:

  01.30: Lenz's law concerning the directi fty9g .tu 2b,2h(, yug7qspsjon of an induced current in a conductor by a magneticsh,jtyygqu,s2 f( 9g .ubp2t7 field could be a restatement of

  11.25: The product (3 Teslas) × (2 meters) × (4 meters/second) is equq ).aa cnw5cmkx /9hd0m2 yu(sivalent to which on yh)qwm .9s(ud c/nam2kx0 a5ce of the following?

  04.34: A square loop is placed in a uniform magnetic field po dar :e3)tj)merpendicular to the plane of the loop as shown. The loop is 0.5 metemot ))jeda :3rrs 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 int:o7 na4mkb+u /n m;teeo the page. The wire experiences an induced char; na+ t:/eekm7b4noumge separation as shown. Which way is the wire moving?

  00.20: A wire moves with a velueks*x, n7 vl-hz)s6iocity v through a magnetic field and experiences an induced charge separation as slh x,s67zsik-vun )e*hown. What is the direction of the magnetic field?

  05.33: The figure below shows a bar moving to the right on two w+r hsn9n1w)o )3kzk jconducting rails. To make an induced current i in the direction in3)wwknk1j+no r z)9hsdicated, in what direction would the magnetic field be in the area contained within the conducting rails?

  00.10: When a wire movwd/+ (k;cud//i ihhening through a magnetic field has a voltage induced between th k /(ndceii/; hdw/u+he 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 m/s traveling throughvci/hz7suf 7/k;g za 1 a uniform magnetic field of 0.060 T. The rod, velocity, and magnetic field are all mutually perpendicul az; 7uf/cg7zv/s ihk1ar. What is the potential difference induced across the rod’s length?

  04.42: A solenoid is oriented end-on so that its opening is perpendicg :aqrqhr+ 0bn1/ohk;ular 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 knhoq g:0+rhr q1/b;a 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 assumed to be close k(6pyt1ab ai(to each other), the resistance of the left-hand circuit is slowly increased. In which direction does the galvanometer ny (ak6(ib1 atpeedle in the right-hand circuit move in response to this change?

  08.29: A strong bar magnet is held very close to the openineybj:)j a /sv3n-rdrv8w2pc ) g 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 of the induced currenbw3s2jn -e )ycdp8 vvra/:j )rt?

  09.37: For the figure shown, the v*eyxk0es*k fs dfmv76j q, (.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 t vy,v.s m *j (keqf*607fsxkdehe 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 clobpg /4x(d +j5 b0vvhjs p4p e:7gbvbc-se to the opening of a solenoid as shown in the diagram. As the magnet is moved to the left toward the s4pe v/dcvbgbb:jjpg7 5b+0 sx-4 (pvh olenoid, 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 to eachi;8kux2 e5 ipb other as in the figure. The circular loop on the left is connected to a constant voltage sourebup; 2i5 k8ixce 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 u32ac f)ka/ g6xd e6scthe 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 of the inner -evv 0dmk7*fq:cwyj5circuit $R_{inner}$ 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 ussv4rrns. (5lcjv/. a plane perpendicular to a spatially uniform magnetic field po5s u./l s rcvv.r4sjn(inting 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 wire with co/yb 91;. 9tpg kxw0hxwmawvi)nventional current directed 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 occurwghx/ ym19kivx.9 t 0 w)wap;bs?

  17.35: A metal bar is moving to the left ac5l vccs3jn.w +w9 n+utross 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 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 n5u+3v .lcc9nw ws+jtmagnitude of the currents through each resistor at the instant shown?

  08.50:. An infinitely long solenoid passes t lj eeap717rin:c o; guw4s*2khrough the circuit as shown. The magnetic far wn7s2*ojeck1 47u eip ;:glield 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 t:6qhrh n vwij9ncu1)8vb pg9az* p0)vime. 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 co)9icvwz ga0v96ub1 hn) p8:qvr*phnjnnected to the corners through the center of the loop. What is the magnitude of the voltmeter’s reading?