94.20: A magnet is dropped bz;f5(qxk w 5hm1l9wb c5aq8gthrough a vertical copper pipe slightly larger than the magnet. Relative to the speed it would fall in air, the m5 a;9mc85wlgwqz b5xf1b (qh kagnet in the pipe falls:

  01.30: Lenz's law concerning the dire2 0(jl+w rkb-qxjlfk0ction of an induced current in a conductor by a magnetic fielk(bfj0lq j-+0r 2kx wld could be a restatement of

  11.25: The product (3 Teslas) × (2 meters) × (4 meters/second)unrc)u6)kx x ( is equivalent to whicku(u ) xxcr)6nh one of the following?

  04.34: A square loop is placed in a uniform magnetic f 9qt kt;l(hw5lel7hq0u, dj)jield 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 looptt9 hj jq5;u(l,e7w0dqhl l) k 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. T 2cs6 r 5hdncrpx7d.0whe wire experiences an induced charge separation as shown. Which way is the w27cxcnh 5p0.rdds6w r ire moving?

  00.20: A wire moves with a velocity v through a magnetic field and experienvu ;n*n, )nh4e k2niqvei q24zces an induced charge separation as shown. What is the direction oi4nni k42ueeq*v;v h n2z,q n)f the magnetic field?

  05.33: The figure below shows a bar moving to the right on two conducting raino+i:3b gt 7pwzezy5un*;w0b ls. To make an induced current i in the direction indicated, in wh:b bty ;nz+*wu0nz 75og piw3eat 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 induced betwa k)zx2k 66.rtod5 fpneen the w tox f6)pn6dkrk5. 2azire’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 4 z lhkq;.o+kjm/s traveling through a uniform magnetic field of 0.060 T. The rod, velocity, and magnetic field are all mutually perpendicular. What is th4o+qjk; kh. zle potential difference induced across the rod’s length?

  04.42: A solenoid is ori hox3n *(b /nlf(or*qwented end-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 addedhbno(owqf( r/3n*l* x 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 brightest to dimmest.

  07.34 For the solenoiy8mr1+idte y s(51 d8pruy 4dmds shown in the diagram (which are assumed to be close to each other), the resistance of the left-hany8y mdd pi(yrm5+ 114 dre8tusd 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 h7c-o uxt4xe 4zn/ :fiqeld 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 s74- i t4cf/qo:xexzu nhown and what is the direction of the force on the magnet because of the induced current?

  09.37: For the figure shown, the9(f7 e ubyhtff0v7m l0 variable resistance in the circuit on the left is increased at a constant rate. What is the direction of the magnetic f v7bty 0f7f9mu(l0h efield 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:te,ej(2ltk1hi,imi h ak xz.ilb .+0 to 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 dir be1lm:,iheki,..h ti0x+jl2 tak i (zected 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 plac ywn*wmtv gjj+c3vz:o9k6(j6 ed next to 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 linearly with time. As the resistance is changinvov9 cwn(wy6j3g m tk*z6:j +jg, 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 the o/dd ygg9a0q k 3g /6qj/ffm4b m4wdhme ;2fb6nuter 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 figur5tlr ip rt,5)ve shown, the variable 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 plane perpendicuqy,hhcxm6 q )3lar to a spatialx q h6yqh3mc,)ly 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 increase?

  16.47: Two small loops of wire are located close to a wire wit8zxdmtzvib9qu )i,,k*8+ y rh8do w7jh conventional current directed up the page. A scientist then moves the loops away+bt88zywh9djr 7x*iduim)v,kq o,8 z 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 mov+okdpi w66o;28gq b *p-rwjxzing to the left across a set of frictionless conducting rails as seen in the figure. Throughout the region between the rails, there is a 682opgow kd*;p-qj x+wrzi 6buniform 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 at the instant shown?

  08.50:. An infinitely long solenoid passes through thb-mb2 p,.y rux-pfw d*e circuit as shown. The magnetic field offyxbp2,-b *dr.u- pwm 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 o2 q6/c-k4ca y 6acgfyyx r)*wtime. A constant emf ξ is produced for the square loop enclosing the field in the figure. The square loop hasfoy-xq a426g *ccy)/ cw y6kar 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?