94.20: A magnet is dropped througl3;ue v 41y;qrph rm2orz(ihiq/lx3;h a vertical copper pipe slightly larger than the magnet. Relative to the speed it would f3ie hqvri ol hr;1y4q;;/( l3 z2rpxumall in air, the magnet in the pipe falls:

  01.30: Lenz's law concerning the direction xn l br1d)ce4 .quj /yy9gp6v+of an induced current in a conductor by a magnq9yc .jb4+ly1) gd rpex/6 nvuetic field could be a restatement of

  11.25: The product (3 Teslas) × (2 meters) × (4 meters/second) is equivalentl+-m)u a:3)woeai x ks to which one of the om+sa e)3a:iw-x )luk following?

  04.34: A square loop is placed in a uniform magnetic field perpendicular t rl6) golb*5+ har;liio the plane of the loop as shown. Th)rbihoi;g rlal+65l * e loop is 0.5 meters on a side 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 xr rkp u)vsjje**(5jl)p e, ult/9eq.a magnetic field directed into the page. The wire experiencerj*,tl /sx9p(.e)j *r ekqu jpvu5)els an induced charge separation as shown. Which way is the wire moving?

  00.20: A wire moves with a veloh*;9z syam jk4mt)+oqcity v through a magnetic field and experiences an induced charge separation as shozy h)som4j*qm; tka+9wn. What is the direction of the magnetic field?

  05.33: The figure below shows a bar moving to the r hs ps)a7 (o8zs7)obsxight on two conducting rails. To make an induced current i in the direction indicated, in ws8a bh7sz)7ossxpo)(hat direction would the magnetic field be in the area contained within the conducting rails?

  00.10: When a wire moving through a magneti i8w *hcxjtyhc.s( y50c field has a voltage induced between* .ci(yst0yh8h x cj5w the 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 velog3y+8jo;* qf7x lskpecity 0.30 m/s traveling through a uniform magnetic field ooxsg8 3qep+ flk j7y;*f 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 asm :vba;jrt9 itjzr12j 0z 4+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, decreases uniformly in time at the same rate forj9 rz1tz20mabr 4sj+vijt:;a 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 assumed to be clossxf6 v 7vv14xue to each other), the resistance of the left-hand circuit 6vs1fvx ux47v 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 magnet is held very close to the opening of a solenoid asq39s (uyt8d9 9uj )m9quxy9j yt4eipu shown in the diagram. As the magnet is moved away from the solenoid at 9uy jy9t qsu()9t e9uuxq9dp3y8j im4constant speed, what is the direction of conventional current 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 the lef3xkxt )kmcg do32)+xct is increased at a constant rate. What is the direction of the magnetic field at the point P a)c3x2 xxgck3mkto+d )t 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 very close to the opening of a solenoid as egifaz1r xp+278ectk,*:mr,, r4v,f zr bbcfshown in the diagram. As the magnet is mo bb8zrr,*kcc:zt41r+ffvg2,r7e f emxi,ap, ved 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 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 next to each othereejxt /tjkgi ev x53omy14)1. :px k7g 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 mt)x135tvix e7p:kk yj1gme . jg/e4oxagnetic 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 shown, the variable resistance of the o5 4 u)fs30*tn,m9 vtmq(fjc1cbk3 yjt-yjqututer 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 variab*0u tej5y;edtg3b /ayle resistance 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 s 4o9 qu ;+oighzk8(duhits 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 followingh 8dh zq4u9 k(go+oui; effects best describes the result of this field increase?

  16.47: Two small loops of wire are located close to a wireurdyyhq 228* d,sswr ( with conventional current directed up the page. A scientist then moves the (w82ry *drys s d2q,hu 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 lef3q 7 3syhn7kntt across a set of frictionless 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 between the magnitude of the currents through each resistor3 7hstn3q7 ynk at the instant shown?

  08.50:. An infinitely long solenoid passes through the circuit as shotlzn3pls)9 ; enarx8; wn. The magnetic fienlpa;x83ezr 9tsl) ;n ld of 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 the plane of the page is decreasing ing i)* s:c-hldl time. A constant emf ξ is producel)c:h isgl*d-d 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?