University Physics Young and Freedman Chapter 29 Concept Questions and solutions Chapter 29: Pre-Chapter Question Q: What would happen if the card were not swiped, but just sat motionless in the reader's slot? A: To induce an emf in the card reader's circuits, the magnetized strip on the credit card must move past the circuits. If there is no motion, there is no induced emf or current and none of the credit card's information is read. 1. None 2. In example 29.2, what would be the magnitude and direction of the induced emf if the magnetic field increased at a rate of 0.300 T/s? The direction would be reversed and the magnitude would be 0.3/0.2 times as large. 3. Suppose the rod in Example 29.6 were moved to the left at a constant velocity. Use Lenz's law to determine which direction the induced current would flow around the circuit in this case. The area of the loop and the magnetic flux are now decreasing. The induced current would flow clockwise around the circuit to generate a magnetic field to oppose this
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