PHYS 1B Lecture Notes - Lecture 1: Magnetite
Document Summary
History of electricity and magnetism: 700 bc ancient greeks: amber rubbed with wool attracted straw (electric force, electric from elektron meaning amber, magnetite attracted to iron (magnetic forces, magnetic names after magnesia where magnetite was discovered. Electric force (electrostatic force: can be detected with balloons, electric forces can be attractive/repulsive force decreases with increasing distance between objects. Properties of atoms: normally, the number of protons = the number of electrons, net charge normally 0, when object rubbed together, electrons can be transferred. Why do 2 balloons repel after rubbing on hair: transfer electrons from hair to balloons, both balloons end with negative charge and repel each other. 2 balloons can attract: rub balloons on different material, on hair transfers electrons from hair to balloon, on plastic wrap transfers electrons from balloon to plastic wrap, 2 balloons with opposite charges attract. Clicker question: what happens if you rub 2 balloons with plastic wrap: they will repel (both have positive charge)
