1.
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The animation shows a top view of four wires and a galvanometer in the lab. Current flowing into the + terminal, i.e., counterclockwise, will deflect the meter to the right. During the time interval t=2 s to t=8 s a magnet is slowly pushed completely through the rectangle from the bottom toward the top. (You can also think of the magnet as being pushed out of the computer monitor toward the user.) Observe the meter reading during this simulation. Which pole was inserted first? North or south? The animation starts at t=0 and stops at t=10 seconds. Start.
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| North. |
| South. |
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2.
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The animation shows a top view of four wires and a galvanometer. There is a constant magnetic field passing through these wires. Determine the direction of this magnetic field by click-dragging the black wire back and forth and observing the galvanometer reading. Remember that current flowing into the + terminal, i.e., counterclockwise, will deflect the meter to the right. Start.
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| Toward the top. That is, out of the computer monitor. |
| Toward the bottom. That is, into the computer monitor. |
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3.
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A loop of wire sits in a time varying magnetic field (a positive magnetic field is out of the screen). You may drag the loop around the animation. Given the flux calculation given above, what is the magnitude and direction of the emf induced in the wire during the animation? Start.
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| 3.9 V counterclockwise. |
| Insufficient Information. |
| 39 V clockwise. |
| 3.9 V clockwise. |
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4.
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A loop of wire travels from the right to the left through an inhomogeneous magnetic field. (The green line is at x=0 is for your reference.) The induced emf in the loop is shown in Volts in the animation. Describe the magnetic field perpendicular to the computer screen. Start.
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| Bz(x<0)=0, Bz(x>0)>0. |
| Bz(x<0)=constant, Bz(x>0)=constant, and Bz(x<0)< Bz(x>0). |
| Bz(x<0)=constant, Bz(x>0)=constant, and Bz(x<0)> Bz(x>0). |
| Bz(x<0)<0, Bz(x>0)=0. |
| Bz is uniform. |
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5.
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The wire on the right is pulled to the right for 5 seconds and then to the left for 5 seconds as shown. Determine the magnitude of the magnetic field passing through the wire rectangle. You may pause the simulation and read coordinate values by click-dragging the mouse at any time. The meter displays the induced emf in millivolts. Start. Interactive Hint More Help Plot the input and output voltage as functions of time. See Giancoli-SE: 29-3.
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| 1 milli-Tesla. |
| 2 milli-Tesla. |
| 3 milli-Tesla. |
| 4 milli-Tesla. |
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6.
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A loop of wire moves to the right through a magnetic field (a positive magnetic field is out of the screen) that abruptly goes to zero at x=0. Given the flux calculation given above, what is the magnitude and direction of the emf the the wire undergoes the field transition at x=0? Start.
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| 19.2 V counterclockwise. |
| Insufficient Information. |
| 19.2 V clockwise. |
| 0 V. |
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7.
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A loop of wire is to the right of a wire that runs up the computer screen (a positive magnetic field is out of the screen). In which direction is the current flowing in the wire? Start.
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| +y direction. |
| Insufficient Information. |
| -y direction. |
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8.
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The above animation represents a moving wire loop in a changing magnetic field (red indicates a field out of the screen and blue indicates a field into the screen). Which animation correctly represents both the voltage and flux through the loop as a function of time?
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| Animation 1. |
| Animation 2. |
| Animation 3. |
| Animation 4. |
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9.
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A transformer is connected to a wall socket as shown above. The graph shows the primary voltage Vp (black) and the secondary voltage Vs (red). How many turns Ns does the secondary coil carry when the primary coil carries Np = 200 turns? Start.
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| 1006. |
| Insufficient Information. |
| 200. |
| 40. |
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10.
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A transformer is connected to a wall socket as shown above. The graph shows the primary voltage Vp (black) and the primary current Ip (red). Assume no heat loss in the transformer. Determine the electrical power send into the transformer. Start.
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| 42.5 kW. |
| Insufficient Information. |
| 30.5 kW. |
| 5.5 MW. |
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11.
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A transformer is connected to a wall socket as shown. How many turns are there in the transformer secondary if the transformer primary has 300 turns? You can read component values by placing the mouse over a component. Start. Interactive Hint More Help. Plot the input and output voltage as functions of time.
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| 50 turns. |
| 70 turns. |
| 300 turns. |
| 1800 turns. |
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12.
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A load is connected to a transformer as shown. What how much rms current flows from the wall plug? You can read component values by placing the mouse over a component. Start. Interactive Hint More Help.
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| 0.2 A. |
| 2 A. |
| 20 A. |
