Exam III review.CT3-1An 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 amountCT3-2A charged particle is orbiting in a uniform B-field in the sense shown.Is the particle positive or negative?A: positiveB: negativeC: impossible to tellB(in)CT3-3A coil of wire carrying current I can rotate freely about an axis in a magneticfield. If released from rest in the position shown, which way does it rotate?A: right side will move out of pageB: left side will move out of page.C: loop will not rotate at allCT3-4A 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 ofthe U and in the same plane as the U. Which one of the following statements is true?A: B has a z-component only which is due entirely tothe 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 z-component.D: B has a non-zero y-component, as well as a z-component.B axis I I A x y z(out)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. True or False? For the loop shown, B dl I z0.A: True B: False.True or False? At point A, the magnitude of the magnetic field is BIro2.A: True B: False.CT3-6Consider 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 thruthe loop.r I ACT3-7. 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 theunlabeled bar magnet must be a A: South pole B: North poleCT3-8A 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: CWB: CCWCT3-9 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: non-zero and upward C: zero S N ? R V B(in)CT3-10A solenoid has an increasing current which creates an increasing B-field in its interior. The electric field at point c isA: up B: down C: left D: right E: zeroAt which of the three points (a, b, or c) is the E-field maximum?A: a B: b C: cD: the E-fields at b and c have the same magnitude and are larger than the E-field 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: No, no eddy currents.a c b I, increasing B, increasing BCT3-12 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: zeroB: 1AC: 0.5AD: some other answerAt t=0+ , what is the current through resistor R2?A: zero B: 1A C: 0.5A D: some other answerAt 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 onlyB: thermal energy only (the resistor is hot)C: electric field energy onlyD: some combination of these three forms of energyIf 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 largeC: 4 times as large. D: some other answerL = 10H V = 10V R2 = 10 R1 = 10 C= 1FCT3-13. A 600W hairdryer is attached to 120VAC circuit. What is the peak current through the hairdryer (to within 5%)?A: 10A B: 7A C: 5ACTIII-14A step-up transformer is plugged into a standard 120 VAC wall socket. The secondary of the transformer is attached to a variable resistor R.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.R V Np
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