94.20: A magnet is dropped through a vertrjrt: -.f t ,r7cse -e*y8rkfiical copper pipe slightly larger than the magnet. Re tcek7 je rit-,r-*sr8f f:yr.lative to the speed it would fall in air, the magnet in the pipe falls:

  01.30: Lenz's law concerning the dirm7f )p oohhb+4 sw69jbection of an induced current in a conductor by a magnetic field could 6bb4+howmh7o s pj)9fbe a restatement of

  11.25: The product (3 Teslas) × (2 meters) × (4 meters/second) is equivaraszy im7l) ky2;uw5 -lent to which one of thel) imyrk7-s5z ; awuy2 following?

  04.34: A square loop is placed in a uniform magnetic field perpendicular to the 3jbw5/ j fa2zv:f1*.n;ajifn jm6hd a plane of the loop as shown. The loop is 0hnn*afmf; 3 2/w16v5ajfj.:bz ad ji j.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 idny9m 2mlj)g2z dj9;n nto the page. The wire experiences an induced charge separation as shodnj jyd) m9 m2ln9;g2zwn. Which way is the wire moving?

  00.20: A wire moves with a velocity v through a magnetic field and experiencerbxp -.2eq k3rs an induced charge separation as shore2xb.q - k3rpwn. What is the direction of the magnetic field?

  05.33: The figure below shows a bar moving to the right on two conducting rail)j52 yfnx-w tis. To make an induced current i in the direction indicated, in what directioyx2) -ni f5twjn would the magnetic field be in the area contained within the conducting rails?

  00.10: When a wire moving through a magne- ,y/tz*txgwu +ls,-pwgs6gftic field has a voltage induced between t-plg+szww, u, /g gt*xf-sty6he 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 ham ulr*z /5dl(ps constant velocity 0.30 m/s traveling through a uniform magnetic field of 0.060 T. The rod, velocity, and magnetic field are all mu5m(l upd/rz *ltually perpendicular. What is the potential difference induced across the rod’s length?

  04.42: A solenoid is oriented ea4*-rm:d,hbiz ;( ah zhebih 7nd-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 d7e*mbz-ia i;,ah h hb(: h4zrbrightest to dimmest.

  07.34 For the solenoids shown in the diagram (which are assumed ki3sp7gj fz 2k7s/54i eu5y eqv 0yn;qto 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 ch5kn/ii fk7 ;0suszey52ep qv3g y q4j7ange?

  08.29: A strong bar maggxl /+nzxa o)e/8) vkvnet 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 of the induced current? gk8 zxevl)vax //)n o+

  09.37: For the figure showk bk.v w)6wj;an, the variable resistance in the circuit on the left is increased at a constant rate. What is the direction of the magnetic field at .w)6akkwj;vb 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 sybut es1/i)3tolenoid as shown in the diagram. As the magnet is moved to the left toward the solenoid, a conventional current through the resistor shown is directedset/1bu) ti3y 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 qvsqp1 oh3ne/ :jiv /1loops of resistive wire are placed next to each other as in the figure. The circula1hq v :n1/q eo/sj3pvir 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 right-hand loop (as viewed in the figure from above)?

  11.41: For the figure shown,j 9t ztdnacd+,3+jds+ the variable 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 variable resistance of the ruoapc20 j8qe22w6skqy ( 1 dsinnercircuit $R_{inner}$ 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 wi3/b+k1lx rtmh re loop 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 describes the result of this field in/k+h13bxr mt lcrease?

  16.47: Two small loops of 8 gp /7udh0kmda75jbk wire are located close to a wire with conventional current directed up the page. A scientist then moves the loops away from the current as g70 b5 jmuhk8pakd7/d 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 fricti: xa mmxe2h(3 b(8brbdonless 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 magnitude of the currents through each resistor 8rb a:b mhdm(x2ex3(b at the instant shown?

  08.50:. An infinitely long solenoid d/s+-n4yvpsfi aa*+qpasses through the circuit as shown. The magnetic field of the solenoid, directed in+qsy* apv/ sa df-+ni4to 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 directedrq62t- vns wr st5cz86 into the plane of the page is decreasing in time. A constant emf ξ is produced for the square loop enclosing the field-5sn ttqcv62w6zr8r s 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?