94.20: A magnet is dropped through a vertical copper pipp:bzevbi*h(c4.i: yq26r a v-k unr-le slightly larger than the magnet. Relative to thy - ilq4b.pch2 :6 *kruv:nzrva(i-eb e speed it would fall in air, the magnet in the pipe falls:

  01.30: Lenz's law concerning the direction of an induced currski nf8g *l+u2ent in a conductor by a magnetic field could be a nsu2 g8li+fk* restatement of

  11.25: The product (3 Teslas) × (2 meters) × (4 meters/second) is no;v 06* v: by3ue1xzdq1 5:gsaptajsequivalent to which one of the folu b; dzpq5y3sn::0a6 11esaov*xgjvt lowing?

  04.34: A square loop is placed in a uniform magnetic field perpery ly,6mo t9pw (dqvq j-4/4bvndicular 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 thpdq-( vorw/4m4 ,btyj y69lvqe 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. The w4q0g.y4 ;zgp inhc1zz ire experiences an induced charge sepa.1; 0zghz4i4qgzpn ycration as shown. Which way is the wire moving?

  00.20: A wire moves with a velocity v through a magnetic f4s rwx8.k 7rhlegv.3uield and experiences an induced charge separation as shown. What is the direction of the magnetvrewhs4 u8 r3.xkl 7.gic field?

  05.33: The figure below shows a bar moving to the righe0 179hxrm(xy sz maq+*k)t:mopz)e mt,9syo t on two conducting rails. To make a( te am+: hors0o1m,qzm)pkyz 9 m* ex97txsy)n induced current 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 magnetc-+dzd ,hp 4ywic field has a voltage induced between the wire’s ends, thazyh , 4wdpd-+ct 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 longkq;x 6ybex9m2 ijapz6c 8 )qb4 copper rod has constant velocity 0.30 m/s traveling through a uniform magnetic field of 0.060 T. The rod, velocity, and magnetic field are all mutual z4qaemb ibx;cj6p yk9)x 8q62ly perpendicular. What is the potential difference induced across the rod’s length?

  04.42: A solenoid is oriented end-on x.rkv4td s,h6 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, decreases uniformly in time at the same rate for each circuit. Rank the circurh.xv4,st kd6its for the brightness of the bulb labeled R1 from brightest to dimmest.

  07.34 For the solenoids shown in the diagram (which are assume.-tawrsk-lt p,-i +evd to be close to each other), the resistance of the left-hand circuit is slowly increased. In which directiowse a,tv- ltpk.i--r+ n does the galvanometer 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 of a solenoid as d 84ze+1 r/fiamwpm.mv)d,fd p.- n kashown in the diagram. As the magnet is moved away from the solenoid at constant speed, what is the direction of conventional current through the resisf8,pmpv/d w1 4zdi. fmkamdne ). -ra+tor 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 resisthsp (q4tlyd6 3y c*y1xance 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 l6 y*s1 (yy3t4c qpdxhthe resistor in the right-hand circuit?

  10.39: A strong bar magnet is held very close to the op6q)qn :f5ep itening 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 bar magnet be:6fqt 5 pin)eqcause 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 8uhf4 p6ixj4txu2)w c 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 tf x t)cju4hpiw6 2xu48ime. 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 figure from above)?

  11.41: For the figure sh p +w cazies.9wdbp(-4a9hwp5own, 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 thi tzj-5 mcce-;gt n;1me 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 ph 8-df 0ybw9r 3 n xxe;2ibc.yn,olnt6erpendicular to a spatially uniform magnetic field pointing into the plane of the page as shown. Th ;obhyn09.3xeli xn8b- 62nwd,rfytce 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 are located close to a wire with conv(y8a)(jyyqq vt 3u6uwentional current directed up the page. A scientist then u j8(3)qyw aqty(vuy6 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 the left across a set of frictionless conhf+uilx:u u a0 7a1o;kubd /j:ducting rails as seen in the figure. Throughout the region between the 0dahk;/u :ibu u :+ajlxo f7u1rails, 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(kz wngwd1 8f6 solenoid passes through the circuit as shown. The magnetic field od1w (6k zwg8nff 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 directed into t 7 48sypz1hx1jos.kz5n hwkj)w-z b3phe 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 bw3z4zyj7-xpw5)k.hhs j pzo s81n1k it and an ideal voltmeter connected to the corners through the center of the loop. What is the magnitude of the voltmeter’s reading?