Physics; The Foundational Science

Chapter 25 Current Generation

Questions 6,8,9,11,12

Questions 1. When a straight conductor and its 11. What five principles did Faraday demon- motion are perpendicular to each other strate with a coil and a bar magnet? and to the magnetic flux, how fan the direction of electron drift be predicted? 12. What is the equation giving the induced emf in a coil? 2. When will the drift referred to in the previous question cease? 13. When Faraday thrust the south pole of a magnet toward the end of a coil, what 3. The force on a moving charge depends magnetic pole was induced at that end? on what three factors? What pole was induced at that same end 4. Define electromagnetic induction. when he reversed the magnet's direction 5. What condition must be met if a current of motion? is to appear in a conducting loop moving 14. State Lenz's law. in a magnetic field? 15. When the crossbar in Figure 25.3 is slid to 6. What is the equation giving the induced the left, does the induced current tend to emf in a single conducting loop? Iden- increase or decrease the flux linkage? tify each symbol. 16. What principle lies at the basis of Lenz's 7. What does the abbreviation emf stand law? for? Why is the term misleading? 17. In a two pole generator with a rotating 8. Show that volts are the same as webers single-loop armature, at what positions of per second. the armature is induced current zero? Maximum? 9. Describe at least three ways a conducting loop may be moved through a uniform 18. Distinguish between AC and DC. magnetic field without inducing current. 19. How does a commutator convert AC to Describe at least three ways the loop may DC? be moved so that current is induced. 20. Name the prime movers used in power 10. Under what circumstances was Faraday plants. able to induce current in the second of two coils mounted on an iron ring? Current Generation 497