F 0b It is the Friday before Spring Break Yet I am here dutifully attending lecture Shouldn t I receive some clicker points A Yes give me the points please B No I am not here so no points for me thank you F 1 A bar magnet is inside an imaginary closed surface S What can you say about the magnetic r r B dA is flux through the surface S A zero B positive C negative D impossible to tell from the information given dA S N F 2 A loop of wire is moving rapidly through a uniform magnetic field as shown True or False there is a non zero emf induced in the loop A loop of wire is spinning rapidly about a stationary axis in uniform magnetic field as shown True or False there is a non zero emf induced in the loop A TT B FF C TF D FT F 3 A loop of wire is sitting in a uniform constant magnet field as shown Suddenly the loop is bent into a smaller area loop During the bending of the loop the induced current in the loop is A zero B in B clockwise C counterclockwise B in F 4 A bar magnet is positioned below a horizontal loop of wire with its North pole pointing toward the loop Then the magnet is pulled down away from the loop As viewed from above is the induced current in the loop clockwise or counterclockwise eyeball N S A clockwise B counterclockwise F 5 A square loop is rotating in a fixed external magnetic field into the page At the instant shown the loop is out of the plane of the page with left side of the loop above the page and coming out of the page the right side in going in The induced current is axis of rotation B in A C Neither B F 6 A loop of wire is near a long straight wire which is carrying a large current I which is decreasing The loop and the straight wire are in the same plane and are positioned as shown The current induced in the loop is A counter clockwise B clockwise C zero I to the right but decreasing loop F 7 Two loop of wires labeled A and B are placed near each other as shown A large current I in loop A is suddenly turned on This causes an induced current in loop B which causes A A net replusive force the two loops repel B A net attractive force the two loops attract C whether the force is attractive or repulsive depends on whether the current in first loop is CW or CCW D No net force F 8 A wire loop moving right enters a region where there is a constant uniform magnetic field pointing into the page B As the loop enters the B field the current induced in the loop is A CW B CCW As the loop enters the B field the direction of the net force on the loop is A right B E there is no net force C up D down F 9 An electric motor consists of a coil free to turn on an axis and located in an magnetic field B created by an arrangement of permanent magnets With the current and field directions as shown which way will the coil rotate A CW axis B B B CCW C the coil I A B won t rotate when at this particular orientation F 10 A solenoid has an increasing current causing an increasing B field in its interior An end on view of the solenoid is shown below An electron is directly below the solenoid While the current I in the solenoid is increasing what is the direction of the force on the electron A B in D electron B C Hint What is the direction of the E field at the position of the electron Think Lenz s Law F 11 A long solenoid of radius R contains a uniform magnetic field B which is increasing at a steady rate B t A t where A is a constant For distances r R from the center of the solenoid how does the magnitude of d E dl B da the Electric field depend on r Hint dt z R A E zero B E 1 r B r C E r D E r2 E E r3 ez j
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