1. Chapter 24 and 25 Test Review 1.What is the relationship between the number of turnings or loops and the strength of the magnetic field? ans: direct, increase = increase ; decrease = decrease 2. What will happen if a straight line conductor is set parallel to the magnetic field lines? ans: nothing

2. 3. What will happen when a straight line conductor is placed perpendicular to the magnetic field lines? ans: electromagnetic induction 4. Material that has a uniform directional domain is called a(n) ______? ans: magnetic 5. How can you destroy a magnet? ans: destroy the domain, temperature, hammer, electricity, stronger magnet

3. 6. According to the right hand rule, in what direction is the magnetic flux moving if the current is running out of your paper? ans: counterclockwise 7. A device that has a center iron core loop with two set of coiled wire wrapped around opposite side the core is called a _____________ ans: transformer

4. 8. Why would a good conductor like copper or gold make a poor magnetic? ans: electrons move too easily 9. What material would make the better temporary magnet? ans: like the core in a transformer, iron 10. Draw a diagram a. That show the magnetic flux of like poled magnets. b. That show the magnetic flux of unlike poles.

5. 11. How strong is the force of a magnetic field with a 45 cm long wire carrying a current of 2A? The magnetic field strength is 0.5T. ans: F = ILB ; F = (2A)(0.45m)(0.5T) = 0.45N 12. What is the force acting on 2 protons traveling at 4.3 x 10 5 m/s perpendicular to a 0.05 T magnetic field ? ans: F qvB ; F = (2x1.6 x 10 -19 )(4.3 x 10 5 m/s)(0.05 T) F = 6.88 x 10 -15 N

6. 13. What is the magnetic field strength of a 2.5 m wire carrying 6 A? The force acting perpendicular to the wire is 0.75 N. ans: F = ILB ; B = 0.75 N / (6A x 2.5 m) = 0.05T 14. What is EMF? ans: Electromotive Force, the force or voltage created when a straight line conductive wire is moved through a magnetic filed. 15. What is the relationship between the EMF and the speed by which the wire is moved? ans: the faster the velocity, the greater the EMF

7. 19. The generator in a cruise ship develops a maximum of 220 V running at 55 A. a. What is the effective voltage? ans: V eff =.707 (220 V) = 155.5 V b. What is the effective current? ans: I eff =.707 (55A) = 39 A 20. What is the effective power in #19 above? ans: P eff = I eff x V eff = (39 A)(155.5V) 6064.5 W

8. 16. Resistors set in series of 2Ω, 4Ω, and 8Ω connected to a 6 V battery. What is the current? ans: 0.43 A 17. The same circuit set in parallel. What is the current? ans: 5.3 A 18. What is the effective current for the circuit set in parallel? ans: I eff =.707(5.3 A) = 3.71 A

9. 21. What type of transformer will go from 30 turnings to 3000 turnings? ans: step up 22. What is the primary current with a secondary current of 2A? ans: Is / Ip = Ns / Np ; 2A(3000)/30 = 200A 23. If Vp is 12 V, what is the Vs ? ans: Vs / Vp = Ns / Np ; 3000(12 V) / 30 = 1200 V

10. 24. How can you increase the strength of an electromagnet? ans: reduce resistance, increase the number of tunings or loops, decrease the temperature, use better conductors. 25. What is the formula to find the force acting on a straight line conductor? ans: F = ILB 26. What is the formula to find the force acting on a charged body within an magnetic field? ans: F = qvB

11. 27. What is the formula to find the EMF? ans: EMF = BLv 28. How do you find the effectiveness of a current? Of the voltage? Of power? ans: Ieff =.707Imax ; Veff =.707Vmax Peff = Ieff x Veff 29 Like poles of a magnet will? ans: repell 30. Unlike poles of a magnet will? ans: attrack