18 Einstein de Haas, Stern Gerlach, Zeeman, Lasers, MRI

18 Einstein de Haas, Stern Gerlach, Zeeman, Lasers, MRI -...

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Unformatted text preview: Physics 13 Lecture 18 Prof. H. Gallagher 1 Plan for Today 1. Organization items 2. Angular momentum and magnetic fields 3. Spin 4. Experimental evidence and applications Einstein-de Haas experiment Stern-Gerlach experiment Zeeman effect Magnetic resonance imaging 5. Multi-electron atoms Spectroscopic notation The periodic table 6. Lasers Physics 13 Lecture 18 Prof. H. Gallagher Items There will be a special guest lecturer this Thursday, Prof. Fio Omenetto from the Department of Biomedical Engineering will describe his work in ultra-fast optics and biomedical applications. Next Tuesday there is no lecture. Next week there is no recitation or HW. Next Thursday (11/13) there is an exam! The exam will be held during class (4:30-5:45 pm) A notes page is allowed Constants will be provided like last time The exam will cover chapters 4-7 Exam 2 from 2006 with solution is available on Blackboard. 2 Physics 13 Lecture 18 Prof. H. Gallagher 3 Hydrogen wave functions n : principal quantum numbers 1,2,3 l : angular momentum quantum number 0,1,2,( n-1) m l : magnetic quantum number 0,1,2,, , l ( m s : spin magnetic quantum number 1/2 ) E n = 13.6 eV n 2 Orbital Spin Quantum Number l=0,1,2,(n-1) s=1/2 Length of vector z component Magnetic quantum number m l =0,1,2,, , l m s =1/2 Magnetic moment L = l ( l + 1) S = 3/4 L z = m l S z = m s l = ( e /2 m ) L s = ( e / m ) S factor of 2 predicted by Dirac equation Orbital and intrinsic angular momentum are related to the magnetic properties of electrons / atoms. They can be studied by applying external magnetic fields (e.g. Stern-Gerlach expt) Physics 13 Lecture 18 Prof. H. Gallagher 4 Measuring angular momentum I n A current loop has a magnetic dipole moment: In a uniform magnetic field it will experience a torque that will align the moment with the magnetic field. In addition, for a non-uniform magnetic field the dipole experiences a net force. = IA n A U = B B Physics 13 Lecture 18 Prof. H. Gallagher Angular momentum and magnetism 1) Orbital motion of charges creates magnetic dipole moments. there is a link between the magnetic properties of materials and the orbital motion of the electrons! --- Einstein-de Haas experiment 2) Magnetic dipole moments in an external magnetic field have potential energy that depends on the orientation between the dipole and the field. the dipole and the field....
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This note was uploaded on 10/19/2009 for the course PHY 13 taught by Professor Garyr.goldstein during the Fall '04 term at Tufts.

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18 Einstein de Haas, Stern Gerlach, Zeeman, Lasers, MRI -...

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