Exam III review CT3 1 An electron and a proton have the same momentum p mv and enter a region where there is a uniform magnetic field Which particle is bent more A electron B proton C both are bent the same amount CT3 2 A charged particle is orbiting in a uniform B field in the sense shown Is the particle positive or negative B in A positive B negative C impossible to tell CT3 3 A coil of wire carrying current I can rotate freely about an axis in a magnetic field If released from rest in the position shown which way does it rotate B I A right side will move out of page B left side will move out of page C loop will not rotate at all axis CT3 4 A long U shaped wire carries a current I in the sense shown Consider the magnetic field B at the point A which is equi distant from the two corners of the U and in the same plane as the U Which one of the following statements is true I A B has a z component only which is due entirely to the bottom segment of the U B B has a z component only which has contributions from the bottom and sides of the U C B has a non zero x component as well as a zcomponent y x z out A D B has a non zero y component as well as a zcomponent CT33 5 A long U shaped wire carries a current I in the sense shown Consider the imaginary loop of radius r centered on the right side of the U as shown r A I True or False For the loop shown A True B False z B dl 0I True or False At point A the magnitude of the magnetic field is B A True B False oI 2 r CT3 6 Consider the following configuration of B field lines solid lines and the imaginary rectangular loop dotted line Which one of the following statements is true A There must be a non zero current thru the imaginary loop going into the page B There must be a non zero current thru the loop coming out of the page C There is no current going thru the loop CT3 7 A bar magnet with the ends properly labeled N and S is placed near an unlabeled bar magnet as shown The magnets attract The left side of the unlabeled bar magnet must be a A South pole B North pole S N CT3 8 A circuit with a battery and a variable resistor is near a loop of wire as shown When the resistance R is decreased the induced current in the loop is A CW R B CCW CT3 9 A metal bar not attached to any outside circuitry is moving through a uniform magnetic field as shown The electric field E within the bar is A non zero and downward B in V B non zero and upward C zero CT3 10 A solenoid has an increasing current which creates an increasing B field in its interior The electric field at point c is I increasing B A up increasing B down a C left b c D right E zero At which of the three points a b or c is the E field maximum A a B b C c D the E fields at b and c have the same magnitude and are larger than the Efield at a CT3 11 A uniform solid sphere of copper rotates about a stationary axis in a uniform magnetic field B Are there eddy currents A Yes there are eddy currents B B No no eddy currents CT3 12 The switch in the circuit below has been closed for a long time and then is opened at t 0 What is the current in the inductor at t 0 A zero R1 10 R2 10 B 1A V 10V L 10H C 1F C 0 5A D some other answer At t 0 what is the current through resistor R2 A zero B 1A C 0 5A D some other answer At t 0 what is the voltage across the capacitor A zero B not zero At t 0 energy that originally came from the battery is now in the right half of the circuit in what forms A magnetic field energy only B thermal energy only the resistor is hot C electric field energy only D some combination of these three forms of energy If the inductance L was doubled 20H instead of 10H then at t 0 the magnetic field energy would be A the same as before B twice as large C 4 times as large D some other answer CT3 13 A 600W hairdryer is attached to 120VAC circuit What is the peak current through the hairdryer to within 5 A 10A B 7A C 5A CTIII 14 A step up transformer is plugged into a standard 120 VAC wall socket The secondary of the transformer is attached to a variable resistor R V R Np Ns As R is reduced the voltage Vs across R A remains the same B decreases C increases As R is reduced the current through R A remains the same B decreases C increases As R is reduced the power drawn from the wall socket A remains the same B decreases C increases
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