94.20: A magnet is dropped through a vertical copper pipe slightly larger the)0miwn8e3bhvp 4i/ran the magnet. Relative to the speed it would fall ineb3e vmi/iwh)r4 p0 8n air, the magnet in the pipe falls:

  01.30: Lenz's law concerning the direction of an inducm1g bnfk,s t:6ed current in a conductor by a magnetic field could be a restatement o61gbf tknm:s ,f

  11.25: The product (3 Teslas) × (2 meters) × (4 meters/secondaumbs, i7 2d+z) is equivalent to whichmizsu a+,b 2d7 one of the following?

  04.34: A square loop is placed in a uniform magnetic field per-aq6: amr j,x6,t3 hkkngf oj/pendicular 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 is rotated through a/:a6 -6hx, ,3fmagkkojrntqjn angle of $90^{\circ}$ in 0.1 second what would be the average (RMS) induced EMF in the loop?

  97.32: A wire moves throucw9k.41t -iw j vny 5of/b.wazgh a magnetic field directed into the page. The wire experiences an induced charge separation as shown. Which way is the wire mojwo.v/z w k w41 5bn-cafy.t9iving?

  00.20: A wire moves with a velocity v through a magnetic field and experiencesj:/g /;da8/(l,l h q9 k-cjtqcx wzlms an ilk9gch/,d/m lj(c:8 qxtzq- wl;aj s/ nduced charge separation as shown. What is the direction of the magnetic field?

  05.33: The figure below shows a bar moving to the fo*:g: 67bcbl fxt (kdright on two conducting rails. To make an induced current i in the direction indicated, in what d*:dx:7g bktclbo6ff( irection would the magnetic field be in the area contained within the conducting rails?

  00.10: When a wire mov5 e1nqkc (g:mc tcf095vko(, i:wpe pving through a magnetic field has a voltage induced between the wire’s ends, t: k cck5m 9i:wf5co, g0p( vnp(qevet1hat 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 1u0lac*g sw,/t/l)) gcez oychas constant velocity 0.30 m/s traveling through a uniform magnetic field of 0.060 T. The rod, velocity, and magnetic field are t0a1o ,s/z/)c llwge)c *cgyuall mutually perpendicular. What is the potential difference induced across the rod’s length?

  04.42: A solenoid is oriented end-on so that its open-c1v2nda wcto72/d-,m lb pfd,j q *zeing 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 timeld zw2,- bt- cone cvjm17a,2f d/qp*d 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 suo/6 pecsp .e8hown in the diagram (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-houps8pec6/ .eand circuit move in response to this change?

  08.29: A strong bar mh+yoc7:n v+inagnet is held very close to the opening of a solenoid as shown in the diagram. As the magnet is moved away from the solenoh+n yic +7:nvoid at constant 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 resistf / qp4,+; ptmz7xwxqyance in the circuit on the left is increased at a ,pq x/fwy7 +q4pxzm;t constant rate. 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 the opening of a solenoipa5h,: g/k6 lp(rvrtqe4f4qzd as shown in the diagram. As the magnet i (lprva64zq,k et/h 45 qgfp:rs 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 tgy5f r 4arg ma+1d0ixi/j fa;2o 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 changing, what is the direction of the magnetic field at point P (the center of the left-hand loop) and what is the oriaga;afyrirg+10i4 d 5 /f2jmxentation 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 circugq z: dp+r+-ulh:ldp,u4y z4z *ao0pn it $R_{inner}$ 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 figurv.xiw48gt 9vqx7k: aje 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 plan4x)*hds 6/o n5bpgysue perpendicular to a spatially uniform magnetic field pointb dng/sxoh)pu s6*y4 5ing 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 wire0umum r(q l;)sehds3+ are located close to a wire with conventional curr) s3ud r(h;eumml0q+sent directed 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 t3o*bi *. dixdehe left across 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 identd o .e*3dib*xiical. 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. Thd,u7ccmk 4aj.qo+ fzy. ,9 qt2 bzws*re mag7qou ,b.mq*tz+kywfs,c4z9 .d2a crj netic 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 direc 8ezx7arq/rh /ted into the plane of the page is decreasing in time. A constant emf ξ is /rx azrq8 7eh/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?