94.20: A magnet is drop 0uw- ulppbxi78+2+ mg b8ivdvped through a vertical copper pipe slightly larger than the magnet. Relative to the speed it would fall in air, the magnet in the pi7u+i08g bp8 mi-l+ v2bvpdxwupe falls:

  01.30: Lenz's law concerning the direction of an induced current in a c.eb 26jdqq6v-qjb)kw onductor by a magnetic field coulqw b-6qvqjkj6d2). e bd be a restatement of

  11.25: The product (3 Teslas) × (2 meters) × (4 meters/second) is equiva4 kx tn*hks1q. d*ln7hlent to which one of the followin* kdhs7l4xt* .qhkn1n g?

  04.34: A square loop is placed in auny2pw3v y1j 4 uniform magnetic field perpendicular to the plane of t wjnyyp3v2 1u4he 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 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 d0mjg7sf wlay6 r,pcu,ql *(f8 irected into the page. The wire experiences an induced charge separation as shown. Which way is the qr7a 0lsg ly u,w*fm8j,(6fpcwire moving?

  00.20: A wire moves with a+xo :ojt8x r h y.rksu(2n9s8 obhh /(z4y(nqo velocity v through a magnetic field and experiences an induced charge separation as shown. What is the direxoyys2k osh.((8rnz9qjb 4x: u/ no+ot (8 hhrction of the magnetic field?

  05.33: The figure below shows a bar moving to the right on two conduqydw( opuz 7e.7/c nb,cting rails. To make an induced current i in the direction indicated, in what direction would the magnetic field be in the area conte.yqp7, n7c/ (dwzobuained within the conducting rails?

  00.10: When a wire moving through a magnetic field has a voltage ink- yxkl6l1 a8nduced between the w8 yn-1k6lkaxl ire’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 veloci60wx*b,g:7zd:r rf e6ptqsw gty 0.30 m/s traveling through as t7 pwfg: 6e xr*,zqwbrg06d: uniform magnetic 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 r xm;eh02wjip8q- x 8sits 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 rqhm -xj82exw8pi;0sr ate 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 di px:o/fmmfy; 4agram (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 cyx f/mp4:m;ofhange?

  08.29: A strong bar magnet is held very close to the opening of a solenoid as sn2u3 4 g7xpksemgel95 7(lfhshown in the diagram. As the magnet is moved away from the solenoid at constl9k(3l7gxn p 4 ghees5 msuf72ant 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?

  09.37: For the figure shown, the variable resistance in the cic wjak:98frz ;rcuit 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;9rz8 c jfwk:ad in what direction is the conventional current through the resistor in the right-hand circuit?

  10.39: A strong bar magn in0n4 hg0jfb;et is held very close to the opening of a solenoid as shown in thn nfjghib04 ;0e 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 to each other asip8 c /d.y2(pol w1c2flds0wd 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 fi dp.o2wpl d1yw (d0fcl 8cs2i/eld 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 the outer cdrnmixtobnm*s: 84); d-egi1ircuit $R_{inner}$ 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 variajw8imwxd(cn1 v( sa :,ble 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 loop sits in a t0 v+,1dlm reoplane perpendicular to a spatially uniform magnetic field pointing in,1mv +t odrl0eto 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 ai 96qhs70vvb) ft) szm ngn 1d/ej5j4kre located close to a wire with conventional current directed up th5m f) 69j4dzs)ie jhv1 sgtnknqv/0 7be 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 across a setwk1di kgv4 wd/yq+ vrq/k(f+: 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 indica/f: 1 v+rd4q (/wyq+ kkvgdiwktes 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 0 en 7;hzo4k4 g 0c9dfdk3apsgcircuit as shown. The magnetic field of the solenoi 4g0cf9 hdzknp0;o kde s347agd, 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 decres6 c.1-)zd7u( swj: gfsex0q v7lz wzmasing in time. A constant em e z x)zw76mwvsg0l sc:s-fj( uz7dq.1f 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 connected to the corners through the center of the loop. What is the magnitude of the voltmeter’s reading?