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Unformatted text preview: ENGRI 111 Homework #5 Due Friday, Nov. 2, 2007 1. Write concise answers for the following questions regarding magnetic moments: a. What are the two sources of magnetic moments for electrons? Why? Electrons have two sources of magnetic moments. Recall that a moving electrical charge generates a magnetic field. As the negatively charged electron orbits around the nucleus, it generates a magnetic field (and an associated magnetic moment). This orbital moment can be viewed as a component of the overall atomic magnetic moment. The second, and more important, source of electron magnetic moment is the spin of the electron. Recall that an electron can have either a spin-up or spin-down configuration. This can be interpreted as an up or down magnetic moment, respectively. b. Do all electrons have a net magnetic moment? Why or why not? All electrons have a net magnetic moment. An electron can only take a spin-up or a spin-down configuration; there cannot be some combination that would produce a spin-zero electron. c. Do all atoms have a net magnetic moment? Why or why not? All atoms do not necessarily have a net magnetic moment. The magnetic moment caused by one orbiting electron can be effectively canceled by the magnetic moment generated by another electron orbiting in the opposite direction. A collection of spin-up and spin-down electrons can negate each others magnetic moment and result in an overall zero spin. 2. Briefly explain why ferromagnetic behavior ceases above the Curie temperature. Ferromagnetic behavior depends on the ability of a materials magnetic domains to remain aligned in a preferred direction in the absence of an applied magnetic field. As you increase the temperature of a material, you provide its atoms with...
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- Fall '07