Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Slide 7Electric Field Generated by Changing Magnetic FluxSlide 9Slide 10Slide 11Slide 12TransformerSlide 14A long, straight wire is in the same plane as a wooden, nonconducting loop. The wire carries an increasing current I in the direction shown in the figure.(a) There will be no induced emf and no induced current.(b) There will be a counterclockwise induced emf, but no induced current.(c) There will be a clockwise induced emf, but no induced current.(d) There will be a clockwise induced current in the loop.(e) There will be a counterclockwise induced current in the loop.XA long, straight wire is in the same plane as a rectangular, conducting loop.The wire carries a constant current I as shown in the figure. Which one of the following statements is true if the wire is suddenly moved toward the loop?(a) There will be no induced emf and no induced current.(b) There will be an induced emf, but no induced current.(c) There will be an induced current that is clockwise around the loop.(d) There will be an induced current that is counterclockwise around the loop.(e) There will be an induced electric field that is clockwise around the loop.XA metal ring is dropped from rest below a bar magnet that is fixed in position as suggested in the figure. An observer views the ring from below. Which one of the following statements concerning this situation is true?(a) As the ring falls, an induced current will flow counterclockwise as viewed by the observer.(b) As the ring falls, an induced current will flow clockwise as viewed by the observer. (c) As the ring falls, there will be an induced magnetic field around the ring that appears counterclockwise as viewed by the observer.(d) As the ring falls, there will be an induced magnetic field around the ring that appears clockwise as viewed by the observer.(d) Since the magnet is stationary, there will be noinduced current in the ring.XTwo conducting loops carry equal currents I in the same direction as shown in the figure. If the current in the upper loop suddenly drops to zero, what will happen to the current in the bottom loop according to Lenz’s law?(a) The current will decrease.(b) The current will increase.(c) The current will not change.(d) The current will also drop to zero.(e) The current will reverse its direction.XA conducting bar moves to the left at a constant speed v on two conducting rails joined at the left as shown. As a result of the bar moving through a constant magnetic field, a current I is induced in the indicated direction. Which one of the following directions is that of the magnetic field?(a) toward the right (d) into the page(b) toward the left (e) out of the page(c) parallel to the long axis of the barXA sheet of copper is pulled at constant velocity v from a region that contains a uniform magnetic field. At the instant shown in the figure, the sheet is partially in and partially out of the field. The induced emf in the sheet leads to the eddy current shown. Which one of the following statements concerning the direction of the magnetic field is true?(a) The magnetic field points to the right.(b) The magnetic field points to the left.(c) The magnetic field points into the paper.(d) The magnetic field points out of the paper.(e) The direction of the magnetic field cannot be determined from the information given.XA 2.0-kg rod has a length of 1.0 m and a resistance of 4.0 It slides with constant speed down a pair of frictionless vertical conducting rails that are joined at the bottom. Other than the rod, the rest of the circuit is resistanceless. A uniform magnetic field of magnitude 3.0 T is perpendicular to the plane formed by the rod and the rails as shown. Determine the speed of the rod.(a) 0.38 m/s (d) 5.6 m/s(b) 0.90 m/s (e) 8.7 m/s(c) 2.6 m/sXElectric Field Generated by Electric Field Generated by Changing Magnetic FluxChanging Magnetic Flux E=F/q =qvB/q=vBElectric GeneratorElectric GeneratorΈΈ=NBA=NBAsinsinttNS N SLoop horizontal EMF=maxLoop vertical EMF=0EMFtEmax-EmaxE=Blvsin => E=2NBlvsin=NBAsintwhere =t, v=r=h/2lhQuestion: When a wire loop is rotated in a magnetic field, the direction of the induced emf changes once in each (a) ¼ revolution(b) ½ revolution(c) 1 revolution (d) 2 revolutionAnswer: bQuestion: The emf produced by an ac-generated varies between Emax and (a) 0(b) 1/2 Emax(c) -Emax(d) the back emfAnswer: cTransformerTransformer The output emf of a transformer may be greater or smaller than its input emf A transformer operates on acE1=N1/tE2=N2/tE1/E2=N1/N2E1I1=E2I2 (power input=power output)So
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