94.20: A magnet is dropped through a vertical copper pipe slightly largerzs ,+zzalm/:b than the magnet. Relative to th+ :lzzbs /,mzae speed it would fall in air, the magnet in the pipe falls:

  01.30: Lenz's law concerning the direction of an inducn/ aj0y /6l( )zl6fotnfl1ljged current in a conductor bglz to6 y6afnl(01/ fj/jll)ny a magnetic field could be a restatement of

  11.25: The product (3 Teslas) × (2 meters) × (4 meters/second) is eqbi (.n8esk/ fuuivalent to which one (sknu8ei/b.fof the following?

  04.34: A square loop is placed in a uniform magnetic field per vg lpyu:lm:/8pendicular to the plane of the loop as shown. The loop is 0.5 meters on a side and the/:vp gl:u8lm y 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 i;59 uqge4*xq.*evfoi)oi j mpage. The wire expo4j*;f9uqvegem 5 q)o.xii* ieriences an induced charge separation as shown. Which way is the wire moving?

  00.20: A wire moves withq/hdsc; g+qj4 e*/0j q;mimzf a velocity v through a magnetic field and experiences an induced charge separatige+4q0mdm / ; fh/ szjq*;qcjion as shown. What is the direction of the magnetic field?

  05.33: The figure below shows a bar moving to the right on two conducting railsjij : j j8r30j+1(qwrh4cuhhs. To make an induced current i in the direction indicated, in what direction would the magne4jsuhj8qrr3 +hc:hjj(10ijwtic field be in the area contained within the conducting rails?

  00.10: When a wire moving through a magnetic field has a volr/ ydzvm(v0; ptage induced between the wire’s endm (;vprvd/z0y s, 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 hv+/ovw0(xqu 2t8 qx7 ncp8gqx as constant velocity 0.30 m/s traveling through a uniform magnetic field of 0.060 T. The rod, velocity, and magnetic field are all mutually perpendicular. Whatvpc88( t wo+07gqunx/qx x2 qv is the potential difference induced across the rod’s length?

  04.42: A solenoid is oriented end-on so that its open6gi;4r5 ltp0we j+w yx59knqning 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 circuits for the brightness of the bulb labeled R1 from brightee iwykn6qg0nx9 r5 jwl5+pt;4st to dimmest.

  07.34 For the solenoids shown8ft*t9 ;nt yvr in the diagram (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 tttn8v9y*rf; right-hand circuit move in response to this change?

  08.29: A strong bar magnet is hekojz: we8bt 7f-v3i -sld 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 current through the resistor shown and what is the direct-8se37jb:tkizfv o w- ion of the force on the magnet because of the induced current?

  09.37: For the figure shown, the variable resistance in the circuit uv 9z47el o/a(dyoof3on the left is increased at a constant rate. What is th 9 o/3u7foyeo4l vzda(e 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 c t f91hiy5n6vis 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 resistor shown is dcih6 yt19n5v firected 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 place beq-ff4zaseehg t,wu: 3r633d 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 thfre63 q3 -e,hfzg3u s4wbta:ee 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 thew//m7,g)qzh:etyjpf5e eo q*ieyn vm3x)b*9 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 the ;rgp b(uq9 d cz,rqeiwc 52(j8innercircuit $R_{inner}$ 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 a do 7wfkl-n 3/x fz:x2bspatially uniform magnetic field pointing into the plane of txb7xkon 2ff- z:d3 /lwhe page as shown. 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 are located close to a wire with conv 9c+dqall45y r+9nt 99l tjxnyentional current directed up the page. A scientist then moves the loops away from the current as shown.d9c9a9 l ytlj +tr+ l4q9nxn5y What is the orientation of the conventional current in each loop while this occurs?

  17.35: A metal bar is moving (o ,ivau9e: qgto the left 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 o:u9i(goe,q vaf 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 solenoid passes through the circuit as shown. nwj4 )g-+dwgi The magnetic field of the solenoid, directed inigwgn)d+4 -w jto 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 pa9b:uy.io5ix yj8c ,mdge is decreasing in time. A constant emf ξ is produced for the square loop enclosing the field in the figure. The squa 85jidm,. i 9uxcyy:bore 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?