94.20: A magnet is dropped )w,kum fbr,1p, l(cem through a vertical copper pipe slightly larger than the magnet. Relative to the sp,)fbk1u,lmc(, m rwepeed it would fall in air, the magnet in the pipe falls:

  01.30: Lenz's law concerning the direction of an indu,+ vmrw./mtrp1ht g-hejl (bw.y)b)c ced current in a conductor by a magnetic field could be a restatement of mj .whr)b )l(.-tv/ ,prhbym1twe cg+

  11.25: The product (3 Teslanv(xhs74 :okxj1yh t3 s) × (2 meters) × (4 meters/second) is equivalent to which one 7ynk3o jt:(hvhs14 x xof the following?

  04.34: A square loop is placed in a uniform magnetic rra. n3vo 3mi.field 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 sr r.3a.3ov mnitrength 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 fieptt3/d,4 y mfnld directed into the page. The wire experiences an induced charge separt p/fdt4yn,3m ation as shown. Which way is the wire moving?

  00.20: A wire moves with a velocity v through a magnetic field and ex/8gsd)*pp plv+ k31jr)afjgsperiences an induced charge separation as shown. What is the direction o8) dp alj*/vsrgkps3jpfg +1)f the magnetic field?

  05.33: The figure below sho9r ,ts.zu0waz ws a bar moving to the right on two conducting rails. To make an induced current i in the direction indicated, in what d,ruta.9 0ws zzirection would the magnetic field be in the area contained within the conducting rails?

  00.10: When a wire moving through a magnetic field has a voltage induced betweacoe):rh 5f /bka q 1o0cn(fiv55xlmzv7 6p,c en th0frvac k:f1 5,c5mxbp n57e i /)6a l(cozqohve 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 traveling throug+ g5*z+r:s ,r nwvxhagh a uniform magnetic field of 0.060 T. The rod, velocity, and magnetic field are all 5 h nxz:v,a* +rw+ggsrmutually 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 perpendin kb,* zo mtgf-nb8p-2cular to the circuit contain,b * mt-bp8nzk2 g-onfing 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 circuits for the brightness of the bulb labeled R1 from brightest to dimmest.

  07.34 For the solenoids shown in the diagram (which are as54dujw/2d mm9q cfj .isumed to be close to each other), the resistance of the left-hand circuit is slowly increased. In which direction does the galvanometem /2 djic5m.wufdq94 jr needle in the right-hand circuit move in response to this change?

  08.29: A strong bar m* de+gd k)c(y,xbiwytrc)6( wagnet 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 currege d6b(yt)w)dk y +cc,xiw( r*nt 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 resistance in the circuit on twsrd t7 y ogz:x:.cy23he 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 resistor7zy2wo3sx d:.cy :gt r in the right-hand circuit?

  10.39: A strong bar magnetja.jqa,ti 0: u is 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 resistoa .ju,i0qa: jtr 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 wirey r5a9m m-vv3w 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 vma v9w5y r-m3the 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, the vqe:/;ofaoj(:y ooh1 .kjin+ xariable 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 e kp-:wetq:a1 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 plane perpendicula5 .5rlnc1l ab xpr/7fe+z :jckr 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 b:xj5an+cl1k /eb c .7 flrp5rzest describes the result of this field increase?

  16.47: Two small loops of wire are located cl1 ihb hf 9(meoa(djd3.ose to a wire with conventional current directed up the page. A scientist then moves the loops away from the current as shown. What is 9(dfjh1 b.ha(iomde3 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 stqo5nyz ve6c:jzm c35m( )8gconducting rails as seen in the n 5v: c )mszgo8qetm3yzjc65 (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 between the magnitude of the currents through each resistor at the instant shown?

  08.50:. An infinitely loi lsy rm zo2b0:or:(1gng solenoid passes through the circuit as shown. The magnetic field of the solenoid, dire2l 1zor:: 0rms gboy(icted 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 ifu,j7/)xgdn1yhij k zx(g7s o 65zu -rn time. A constant emf ξ is produced for the square loop enclosing the field in the figure. The square loop has three identical lik f/dj(h6urzu7 51jg yg, z-i)xxosn 7ght 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?