94.20: A magnet is dropped through a vertical copper h;j3e ocs i70frg(av8-qjq +y pipe slightly larger than the magnet. Relative to the speed it would f0h7(yro-je i jq q;3csgvf +a8all in air, the magnet in the pipe falls:

  01.30: Lenz's law concerning the direction of an induced current iklwz.m hc(.iui h81j (n a conductor by a magnetic field could be a restatement oklu1 jh(.hm.wi8c (i zf

  11.25: The product (3 Teslas) × (2 meters) × (4 meters/second) is equi ;tv)n vu6ok8ovalent to which one of the v)t;oukv68nofollowing?

  04.34: A square loop is placed in a uniform magnetic field;: ;xb)n/igx ex n(x6kz;iozd( q:oan 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 isne(zigxo:;xnxkn;(a6 d i zb; )xqo /: 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 di t 52q .1cbx0exeakh4irected into the page. The wire experiences an induced t 1cx20ab5.ex4eiqh kcharge separation as shown. Which way is the wire moving?

  00.20: A wire moves with a velocity v thb93lapnpgu ) , ;h(nerrough a magnetic field and experiences an induced charge pg;r( nb3 l9)ph ane,useparation as shown. What is the direction of the magnetic field?

  05.33: The figure below shows +ku syg;p8mwal9z fiq+* (flkin (n( 0a bar moving to the right on two conducting rails. To make an induced current i in the direction indicated, in what direction woua 0ql ;f*flikg w+ p9in(mzk8n(ys(+uld the magnetic field be in the area contained within the conducting rails?

  00.10: When a wire moving through a magnetic field h ha5qi39,n abtas a voltage induced between the wire’s ends, that votah9,bq35ni a ltage 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 travel 9llv2)fafwt 7ing through a uniform magnetic 7wl)29lf tavf field of 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 opening is perpek (fv01aj3,c+fb yuy 69mb vrl8chsq 5ndicular to the circuit containing the two light bulbs as drawn in figure C1. For figu+5qvchjfy0v(s y89b,umck6br 1 a3l fres 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 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 diagra32um ft;z9:b i p8d f(1jgidrnm (which are assumed to be close to each other), the resistan89 iuijt d2f;zdbgfp: r13m(nce 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 mag; z-9 qcghsgthw 2p-p0net is 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 the forc pph 9sgch2gq ztw-0;-e on the magnet because of the induced current?

  09.37: For the figure shown, the variable resistance in the cir .t )j)s7tzgtf 9):dtcq w9nhncuit 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 ci7ht)d.ct tf nzts9g)wj9q) n :rcuit and in what direction is the conventional current through the resistor in the right-hand circuit?

  10.39: A strong bar magnet i(5t +jhl( fdqk jvzb-:s held 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 diql j5 zjfvh b:+t-dk((rected 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 resistivednaxboj)/( i4 wire are placed 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 changing, what is the direction of the magnetic field at point P (the center of the/jad b)xno 4i( 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,) r326tyva*oqp ad9zo 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 ik2a6ut yd . -9 jr;(gybcb.szjnnercircuit $R_{inner}$ 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 l6lm 4s1zpp 2 dbcy6x b7a/gf7loop sits in a plane perpendicular to a spatially 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 fieldy ac 2g4 pbdf/s l716m67xzplb increase?

  16.47: Two small loops 5xh0omz g 5w(jof wire are located close to a wire with conventional current directed up the page. A scientist then moves the loops away from the current as sw5g0m z5ox(hjhown. 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 /(nut xc)t -lpp05 oubconducting rails as seen in the figure. Throughout the region betweexopp(l 5tbu u/ t)c-0nn 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 shown?

  08.50:. An infinitely long solenoid passes throte.4xv3bn g 3vugh the circuit as shown. The magnetic field of the solenoid, directed into v4extb. v3 3gnthe
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 dm52lw.9axyiv ny .vx(5 v50 1yinm ukzirected into the plane of the page is decreasing in time. A constant emf ξ is prodwl v59xmy 5.zvv5m(x k.uay1ny ini02uced 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?