94.20: A magnet is dropped through a vertical copper pipe slptdvgn 5*; (xchmac8 usw824sightly larger than the magnet. Relative to the speed it would fall in air, the magnet in the pipe fal8acsnds g cm(*84 wuh5 vxt2p;ls:

  01.30: Lenz's law conce)ljjt650 co mwrning the direction of an induced current in a conductor by a magnetic field could be a r65 c0otljwj m)estatement of

  11.25: The product (3 vvw))u 2n1. nghlr2b mTeslas) × (2 meters) × (4 meters/second) is equivalent to which one of the m v. v r2uwl12nhgbn)) following?

  04.34: A square loop is placed in a uniform magnetic field perpendiculan.)z8f0 w2iai;n ir dlr to the plane of thefnil)rw0 i.8 2ndi;a z 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(j:8 ibm oaixi/o1* vt magnetic field directed into the page. The wire experiences an induced charge sepb i8:/ o*xvai1tio(mjaration as shown. Which way is the wire moving?

  00.20: A wire moves with a velocity o121 xezdr9j *d:ey2u; h9mpvxe-o llsz0, xkv through a magnetic field and experiences an induced charge separation as shown. What is the direction of the magne,y-j o9u1px9; m z2 eexdeok0* ld: 12zlxrshvtic field?

  05.33: The figure bes/(3j 56 dba jruf0temlow shows a bar moving to the right on two conducting rails. To make an induced current i in the direction indicated, in what direcd /6 ba(tsmj 3fjur05etion 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 induced rj *yl :e62u+hccl-su44 t geni*ekk33+qvvubetween the wire’s ends, that voltage is * *+2 ukl6yn e3u34-+4qctlkucivgesj v r h:e
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.ttpd8mu , +,yjfe )s:p30 m/s traveling through a uniform magnetic field ofpt es p dt)fu:j,y+,8m 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 openibsvhmxx;14z nh* 2 6wing 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 tw;x4h21v*zsnm i6x hbhe 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 dia *v8ktrudm //cgram (which are assumed to be close to e8t du k/r/vmc*ach 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 change?

  08.29: A strong bar magnet is held veryj*vl0(in(exzdu c4j72lge1 f 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 th1j (c0g4n(fljdi*z 7xueev2l e 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 inzpg ne73wy9m, the circuit on the left is increased at a constant rate.p zn9gm y7e3,w 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 resistor in the right-hand circuit?

  10.39: A strong bar magnet is held very close to*r(/cc/ xxg 8z c3vyix the opening of a solenoid as shown in the diagram. As the magnet is moved to the left toward the solenoid, a conventional current through the resistor shown is directed f/y(icx /*zcc38rxgx vrom 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 as dljr9hy76zo 7 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 right-hand loop (as6 zdjyh l7r79o viewed in the figure from above)?

  11.41: For the figure shown, the var4 yg hpo7nxlpro9+ h(r 1eyg0;vrzku+)/8cbr iable 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 d3xdv 2tq6cnm bo7/ 0,iwka s9o:xqh/ 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 pl ayuzsm75/q00wci lh,xnbm 1 6ane perpendicular to a spatially uniform magnetic field pointing into the plane of the page as shown. The magnetic field strength steadily increase6n wy s/ bchxq a0mi05,m7lu1zs 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 witi 8azeb cp.da.(+so,ch conventional current di c8bisz. .c(a, +dpoearected 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 across a set of frictionless conductin 73 r4tc4sgv 6oe-xr hgsf:sp-i/o7ddm ju)0 yg 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 arr0sh6m4g7ss yjpod34 /e -:) croxdt -fuiv g7e 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 circuit as shown. The maialn4 m, v qbt5uwh0./;:kb dfgnetic field of the solenoid, directed into the a,w; nlib /k v54buthm.0 qdf:
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 decrkke liw g+ aq903f 2zy;47 aj+njai1uoeasing in time. 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 idealj7jq3;na4+oz+kyu29a kiwi1flag e0 voltmeter connected to the corners through the center of the loop. What is the magnitude of the voltmeter’s reading?