1. Physics 121: Electricity & Magnetism – Lecture 12 Carsten Denker NJIT Physics Department Center for Solar–Terrestrial Research

2. April 11, 2007Center for Solar-Terrestrial Research Gauss’ Law for Magnetic Fields Gauss’ law The simplest magnetic structure that can exist is a dipole. Magnetic mono- poles do not exist (as far as we know).

3. April 11, 2007Center for Solar-Terrestrial Research Magnetism and Electrons Spin magnetic dipole moment Bohr magneton Orbital magnetic dipole moment

4. April 11, 2007Center for Solar-Terrestrial Research Paramagnetism: A paramagnetic material placed in an external magnetic field develops a magnetic dipole moment in the direction of. If the field is non-uniform, the paramagnetic material is attracted toward a region of greater magnetic field from a region of lesser field. Magnetic Materials Diamagnetism: A diamagnetic material placed in an external magnetic field develops a magnetic dipole moment directed opposite. If the field is non-uniform, the diamagnetic material is repelled from a region of greater magnetic field toward a region of lesser field.

5. April 11, 2007Center for Solar-Terrestrial Research Ferromagnetism A ferromagnetic material placed in an external magnetic field develops a strong magnetic dipole moment in the direction of. If the field is non-uniform, the ferromagnetic material is attracted toward a region of greater magnetic field from a region of lesser field. Magnetization curve and hysteresis loop

6. April 11, 2007Center for Solar-Terrestrial Research Induced Magnetic Fields Maxwell’s law of induction Ampere-Maxwell law

7. April 11, 2007Center for Solar-Terrestrial Research Displacement Current Displacement current Ampere-Maxwell law Inside a circular capacitorOutside a circular capacitor