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Explore the key concepts of gravity, electrostatic forces, charge conservation, and electric fields discussed in three lectures. Learn about charge transport in different materials and how electric fields are characterized and calculated.
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Summary of lecture 1/24/00 • A new fundamental force: • Gravity keeps us on earth • Electrostatic forces keep us together • Two types of charge (+,-) that generally cancel on macroscopic scale • When balance is disturbed we see attraction and repulsion from electrostatic force. • Coulombs law: • Charge is conserved and quantized in units • Charged objects attract neutral objects through polarization
Summary of Lecture 1/31/00 • Charge transport in matter: • Insulator : No macroscopic charge motion • Conductor : electrons move with ease • Semiconductor : Either of the above • Superconductor : Charge moves with no “friction” • E(r) characterizes “conditions” around charged object as measured with “test charge” q • Electric field from a point charge: • Electric field far from dipole r, q +Q -Q +Q d z
Summary of Lecture 2/1/00 v0 • Charge moving through uniform electric field: Projectile motion but • Electric dipole ( ) “lines up” //Electric field: • Electric field from continuous charge distribution • Calculated E(r) along normal to charged line segment Q E r(r’) R r’ r