94.20: A magnet is dropped through a vertical copper pipe slightly large:t h/v k+xt.npr than the magnet. Relative to the speed it would fall in air, the magnet in the pipe h:v p+t .xt/knfalls:

  01.30: Lenz's law concerning the direction of an induced current 2 tcb.b xf-3x6x pi*,i5onawb in a conductor by a magnetic field could be a restatem5 txb xwpbx62.no- cfi,iba*3 ent of

  11.25: The product (3 Teslas) × (2 meters) × (4 meters/second) is equivalentlve9r7tn ,xa9 to which one of the f ,lretnav97 9xollowing?

  04.34: A square loop is placed in kged2p;;.z4/tx pamv a uniform magnetic field perpendicular to the plane of the loop as shown. The loop is 0.5 meters on a s;m/x p2. pd4g;vtzaekide 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. Thhg()dv oujk ;6e wire experiences an induced charge separation as shown. Which way kgdu(jhov ;)6 is the wire moving?

  00.20: A wire moves with a velocity v through a magnetic field a /k4tq aodfu5,oipy/u z /f6q fo*b)7xnd experiences an induced charge separation as shown. What is the direction of thz/46fd/fix7ok)o*qp/yu to, bu f a5qe magnetic field?

  05.33: The figure below shows a bar moving to/o uj20fk 0lyt the right on two conducting rails. To make an induced current i in the direction indicated, in what directif0ok t ujl2/y0on would the magnetic field be in the area contained within the conducting rails?

  00.10: When a wire moving +o(y: rpmal5.ao4e yjthrough a magnetic field has a voltage induced between theamyro+ j(yp5a l.o4 :e wire’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 tra*/xzw(lwm- c, ma5r*i yuviv9 .ul .sxveling through a uniform magne, /sl.r*ui(x- m9 mu xwiyzcv*.vl a5wtic 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 orientgcuurkay.7s+j0t c4 /:x pa;eed 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 added as shown. Assume that the magnetic field from the solenoid, shown coming out of the plane of the page, csa+0rc gj:tueyu7 /;k4.ax p 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 azo+m/and r 3dx,;k*)9 srq wjlre assumed to be close to each other), the resistance of the left-hand circuit is slowly increased. In which direction does the ga/qz xkn ws drm ),+o9jar3*;dllvanometer needle in the right-hand circuit move in response to this change?

  08.29: A strong bar magnet is held very close : 4m1mmngr+njto 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 force on the magnet because o14gmj mnm +:rnf the induced current?

  09.37: For the figure shown, the variabl28q8tm/sr ;ax0t 1 3lddjswyhe 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 circuit and in what direction is the conventional current through the resistor in the rightd; twyr8ql1 axsd8j0m h3st/2 -hand circuit?

  10.39: A strong bar magnet is held very ci z5bv 0ql.-hvlose 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. W v-.qh5il0b vzhat 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 rsmbzq3r1vl nno;6 / 6fesistive 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 left-hand loop) and what is the orientation of the conventional current in the right-hand loop (as viewed in the figuvz /6 6; fbs1nroqmln3re from above)?

  11.41: For the figure shown, the variable resw;d8ss e42awjistance 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 thet.x o1jgj5v ,z 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 perpen1j* yfl ;n1mjmdicular 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 1f n*mjmy;1j lresult of this field increase?

  16.47: Two small loops of wire are l53ri3vn 43gilp3zuhuxv y9o.ocated 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 conventional current in epz n3v4lgu .y3oxvu ih5339irach loop while this occurs?

  17.35: A metal bar is moving to the left across a set of frictionlessu .7) .*rmg*c5rsl ov.lihpq o 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 bro.lou r ) lm.* 5.7hcgqsipv*etween the magnitude of the currents through each resistor at the instant shown?

  08.50:. An infinitely long solenoid pi)tlvwv5 1cd:)wob i,fnyn j61x -;acasses through the circuit as shown. The magnetic field of the solenoid, direct)c ,y jfvliv;nd twow 1:na)6 -1c5xbied 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 tiu l9f)ckgua4 n 68c)teme. A constant emf ξ is puka8 )g9)lc tucnfe6 4roduced 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?