94.20: A magnet is dropped through a vertical copper pix4qnq0 */ c3xd dvoo,qpe slightly larger than the magnet. Relative to the speed it would fall in air, the magnet ixnod/qdx 0 4,oc3vq* qn the pipe falls:

  01.30: Lenz's law concerning the direction of an induced curre:s3 c)eg 87)dcdwzu+e0 xkhs dnt in a conductor by a magxseu)7+s kec 8)cw3d:h0d z gdnetic field could be a restatement of

  11.25: The product (3 Teslas) × (2 0prb1:co ..so tofw(z meters) × (4 meters/second) is equivalent to which one of the folr 1o.b0s:fot(pc zwo.lowing?

  04.34: A square loop is placed in a uniform magnetic field perpendibl7:8p57r ,uni pzfgs cular to the s5nb7ugrf pp7 i8l,z : 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 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 into the page. The pq2unj vc:jutz oof: (70.y3iwire experiences an induced cp (3cj zn:2f:t qji7.vyu 0uooharge separation as shown. Which way is the wire moving?

  00.20: A wire moves with a velocity v through a magnetic field and experiencesy rtv;0qoh m i52vb3)w an in0wbt;q h rm5 v3oy2iv)duced charge separation as shown. What is the direction of the magnetic field?

  05.33: The figure below shows a bar moving to the right on two go+mq9lazo)dh :3rg.7gew07v q1g kcconducting rails. To make an induced current i in the direction indicated, in what direction would the magnetic field be in the area contained witv)qo:1zc hd0 mg7 3qwg9 kor7e+.g galhin the conducting rails?

  00.10: When a wire moving through a magnetic field has ai yphg nx -x:en+(77qg voltage induced between the wire’s ends, that voltage nqp+xxigg:- y7n(h7e 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 0.3v5c;,w:*cq qmw( tq jy1t1mvh0 m/s traveling through a uniform magnetic field of 0.060 T. The rod, velocity, and magnetic field are all m(:vq qmch 5wv;ct *1wmyqj,t 1utually perpendicular. What is the potential difference induced across the rod’s length?

  04.42: A solenoid is hievdo8ix/5lhk (rbqfk3 a:3ni 7 y4/ oriented 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 resistankqdx4o hivl//r(i38en5 37i hf b:kayce 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 brightest to dimmest.

  07.34 For the solenoids shown in the diagram (which are ass qm)kus2lfw-/ t yar(6umed to be close to each other), the resistance of the left-hand circuit is slowly increased. In which directil )q ys6(k-tfarmu2/ won does the galvanometer needle in the right-hand circuit move in response to this change?

  08.29: A strong bar magnet i 99s6 2lz6ccr iq4p8at;p dqcn/hh eb8s 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 thz64 9q;a rh/6d2q9tbhcp n8se8lp ccie force on the magnet because of the induced current?

  09.37: For the figure shown, thevle(9* qc3v 8q6vsfy s 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 the left-hand civc*sv6 syl9(qfv 38e qrcuit 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 clb (b1 bbr4zybeg ,(8j*qstf 2oose 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 th bb8gsf qbb(yjr2tbo*,1(e z4e 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 ea;zv3u zv416ur c))e plcbz6br ch other as in the figure. The circular loop onzb cb)rpv;u4 vz6zr1 6elcu3) 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 shovtw3m(/u,l fg /r2 dkown, 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 inn epv-mqy/5 ar(ercircuit $R_{inner}$ 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 b r(4oht*g(7yk t7 eipplane perpendicular to a spatially uniform magnetic field pointing into the plane of the t(*77 4o ghr(bipkyetpage 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 locatr );)e 5mguxweed close to a wire with conventional current directed up the page. A scientist then moves the loops away from the current as shown. What is the orientation of the )x5meu rw);eg conventional current in each loop while this occurs?

  17.35: A metal bar is moving to the left acro6qle 1 ,tra+g*b nrb3dss 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 magnitude of the currents through each resistor at the instant sh n*b gq,e+l163 drartbown?

  08.50:. An infinitely long solenoid pix*jz8;6, f gqgb)e7apspp z3asses through the circuit as shown. The magnetic7,pqgg f i6ap;j3)* zspe 8zbx field 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 plansgwo1v t )ze7 npxd-92b:be; ue of the page is decreasing 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 ideal voltmeter connected to the corners through the center of the loop. What is the magnw)7nv;oexu s:bd-b2g e tz19pitude of the voltmeter’s reading?