94.20: A magnet is dropped tsja8kj yx3v*xvs( 5qzj-:f t:er 4n t+hrough a vertical copper pipe slightly larger than the magnet. Relative to tkt av5j s83rjy (: zv-xqfstnj:e*4 x+he speed it would fall in air, the magnet in the pipe falls:

  01.30: Lenz's law concerning the direction of an induced current in a fpg:p1*ka+dx0 h +h mcconductor by a magnetic field could be a rhhdg +0p :pmc*xfa k+1estatement of

  11.25: The product (3 Teslas) × (2 meters) × (4 meters/secon- 9uip0lics t4d) is equivalent to which one of the followip it s9l4u0ci-ng?

  04.34: A square loop is placed in a uniformb5uao0nn- liiaq861* xq(xmw 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 has1 minx6bi l0-o xq5uw aa*q8n( 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 fiey p kvq 5j4ilhv.r+9-vld directed into the page. The wire experiences an induced charge separation as shown. Which way is the wire movl 5yvqh jirv9- +k4pv.ing?

  00.20: A wire moves with a velocity v through a magnetic field3az,b: . pspea and experiences an induced c.a,s :3aezp bpharge separation as shown. What is the direction of the magnetic field?

  05.33: The figure below shows a ba5 luiupf7)z4x5 mf, q(z v+gbzr moving to the right on two conducting rails. To make an induced current i in the direction indicated, in what direction would the magnetic field be in the area contained within the conducting ra 5uq vfzpl4(g 7)im5zubz fx+,ils?

  00.10: When a wire moving through a magnetic field has a voltage indu vqp51cm2gw p7*hhsdf9 l-p a:ced between the wire’s ends, that -fph cw:7l9*pq ghvms pd125a 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 m3qp1 5firx7ea/s traveling through a uniform magnetic field of 0.060 T. The rod, velocity, and magnetic field are all mutually perpendicular. What is thx f35pear i1q7e potential difference induced across the rod’s length?

  04.42: A solenoid is ori:;9hpwsx1ub0a,gn yiented end-on so that its opening is perpendicular to the circuit containing the two light bulbs as drawn in figure C1n0ixw:gps uab,1 yh9 ;. 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 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 dias+h(b-a tqlgxs14 xt,gram (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-hand cts h+gat q1sb-4 x(x,lircuit move in response to this change?

  08.29: A strong bar magnet is held very 026;h),kiwqbeuf nzg8a zun+. tw.u t;gvqq8 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 show ,fnw;+q k8 unvgq 6z280bgq;i. )zeuuta.wth n and what is the direction of the force on the magnet because of the induced current?

  09.37: For the figure shown, the vari7fpxma8q9 q8y tybhhu664, fhable resistance in the circuit on the left is inc htaq,mfx8h49y6 uyp8b6fh7qreased 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 right-hand circuit?

  10.39: A strong bar magnet is held veryqpoi 06ursn0 + 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 of the force on the + u6o0 pisq0rnbar 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 nextycbgq2 mob 3)uzi)6b (; 2dtbd 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 orientation6 b 2bb2tcbmz(i dudy)g)q;o3 of the conventional current in the right-hand loop (as viewed in the figure from above)?

  11.41: For the figure (h)tetv4h9w nshown, 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 8e/mzpi( d x+lgxo7sk d2h 5qr-qg6g1the 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 perpendicular to /gbk nvn bdn13*e2dk.,udqu8 a spatially uniform magnetic field pointing into the plane of the page as shn*d1dkn3 knd8, b q .eg/2uubvown. 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 qq ,4yv(m3q h)ly ky0mare located 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 tyq4mymy0l (, hkv q)q3he conventional current in each loop while this occurs?

  17.35: A metal bar is moving to the left across a set of frictionless v9sattqttp(74x0 p9i) 8 knn oconducting rails as seen in the figure. Throughout the region between qnt40p(7n t9 )p ot9xts ivak8the 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 solensb) z (wl51h63duzszc ;+d(q j i7ezswoid passes through the circuit as shown. The magnetic field of the solenozsc; 6sblw +edd7h51 ()q(z z3zj iuwsid, 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 intom(ieo1w( s9km( ( krxy the plane 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 magnitude of the voltmeter’s reading? rimko(x9( ykwm(e1 s(