94.20: A magnet is dropped through a vertical copper pipe s -7(,sbqxjxvwz b 10tplightly larger than the magnet. Relative to the speed it would fall in air,s7, -wx0qt1z bpjxv(b the magnet in the pipe falls:

  01.30: Lenz's law concerning the direction of an induced current in ay 8k *ew7smzw(6r/til conductor by a magnetic field could be a restatemey8zsw/ r(w 6imtl*7ek nt of

  11.25: The product (3 Tu .jw;s bpn *mxsc//,teslas) × (2 meters) × (4 meters/second) is equivalent to which one of the / s.mbu/s wjt* ;,ncxp following?

  04.34: A square loop is placeh4xjynjmx.37(8 u*0e fkond: q u4awn d in a uniform magnetic field 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 loop isq*8xyewnmx :7oj4fnku d0 jn(u.3 4 ha 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 aojs*v(evm(nqan 5h() magnetic field directed into the page. The wire experiences an induced charge separation as shown. Which way is tqvom()(n *an(sjve h5he wire moving?

  00.20: A wire moves with a velocir,7iug:rpmukh :t*a;vkj : r;/xoh6 pty v through a magnetic field and experiences an induced charge separation as shown. What is the direction of thmk: ;:ug*,prk 6 vr7oh/i:t ;xuja prhe magnetic field?

  05.33: The figure below shows a bar moving to th1b62fqhzc5x4 u beljt6z ) a9ue right on two conducting rails. To make an induced curb5 zc1 zf2u66 tj9hu4qb)exa lrent i in the direction indicated, in what 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 voltpmdnoc:f :u*l9sqeyz6 7 h)h 7age induced between the wi7ehph cl7:muq6*9 fz)s :ondyre’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 m/s traveling tq:yn4n 49be sghrough a uniform magnetic field of 0.060 T. The rod, velocity,se :n9gny4 4qb and magnetic field are all mutually perpendicular. What is the potential difference induced across the rod’s length?

  04.42: A solenoid is oriented x7u3-5a+ encvtjri 4 jend-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 mata3rci5v u+-e7 jn x4jgnetic 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 (wh+qe,3 aoqsl s;ich are assumed to be close to each other), the resistance of the left-hand circuit is slowly increased. In which direction does the gae qq3sa,+ lo;slvanometer needle in the right-hand circuit move in response to this change?

  08.29: A strong bar magnet is held very close to the opening ob+,f0 ptf nuc1f a solenoid as shown in the diagram. As the magnet is moved away from the solenoid at constant speed, what is the dir, bcpn uf+t1f0ection 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 res 0*yqabr *,tjsistance 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 centeys**t 0qja,brr 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 h.8t1pff87 m v-axj3dtrdg) wp eld very close 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 directed from A to B. What is the direction dt-.x8j1r pw78f)tg dvmp3fa 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 a-ny 1ub uye8lh-o: 2uhs 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 (tu1h8be :yu- l2u-h nyohe 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, ttbx y-h6wgx 9, ci,m/dhe 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 sho4ix /6*m (yf u svuwt2bfw0ju1wn, 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 su*,n3t9vn0ixnp +a d4dkba9tits in a plane perpendicular to a spatially uniform magnetic field pointing into the plane of the page as shown. The magnetic field strength steadily inc9x9nvnt ud*3anpai t 4db0 +k,reases 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 fb7 3v6i a.skuwith conventional current directed up the page. A scientist then moves the loops away from the current as shown. What is the orientation of the conventional current ivuk7a6 fi s.3bn each loop while this occurs?

  17.35: A metal bar is moving to the left across a set of frictionrvol qb1f,h-q u 5h9/b8gk6bxless conducting rails as seen in the figure. Throughout the region between the rails, there is a uniform ma,q/o5 89lf-g uxrv6b kbb1h qhgnetic 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 f(vv1x8 qqce:solenoid passes through the circuit as shown. The magnetic field of the solenoixv:(vf 1ceqq 8d, 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 ijkap./ec9t0 in 1nrt8 n time. A constant emf ξ is produced for the square loop enclosing the field in the figure. The square loop has three identical lir1nct pt809a/ e.jki nght 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?