1. Electrostatics

The professor begins by outlining the syllabus for the term, focusing on electromagnetic theory, optics, and quantum mechanics. Electromagnetism is introduced as a new force, with optics being a subset. Quantum mechanics is described as a fundamentally different approach, challenging traditional concepts of trajectories and particle motion. The professor emphasizes the importance of quantum mechanics for understanding small-scale phenomena like atoms and molecules, while classical mechanics suffice for macroscopic objects.

The discussion shifts to Newton's famous equation, F = ma, highlighting its subtleties and applications. The professor explains how to measure acceleration and velocity, and how these measurements lead to an understanding of force in relation to mass. The concept of mass is explored, with a clarification that mass is not the same as weight. An example using a spring and a standard kilogram mass is provided to illustrate how mass can be determined experimentally.

The professor demonstrates electrostatics, a new force, using a piece of paper and a comb. Despite the force being much stronger than gravity, it is shown to be overcome by the collective gravitational pull of the Earth. The strength of electrostatic forces is quantified, and the professor discusses historical experiments that led to the understanding of electrostatics, including the behavior of charged objects and the phenomena of attraction and repulsion.

Coulomb's Law is introduced as the fundamental principle explaining the electrostatic force between charged entities. The law is described in terms of charge quantity, measured in coulombs, and the force constant. The concept of charge as a property of certain entities is discussed, along with the historical context of Coulomb's contribution to the law. The vector nature of force is also explained, and the professor emphasizes the importance of understanding the direction of force.

The principle of charge conservation is discussed, emphasizing that charge is conserved locally and does not change over time. The concept of local charge conservation is highlighted as a requirement for a theory that is consistent across all frames of reference. Additionally, the quantization of charge is introduced, noting that all observed charges are multiples of a basic unit of charge, indicating a granular rather than continuous nature of electric charge.

The atomic structure is described, with a focus on the roles of protons, neutrons, and electrons. The identical nature of all electrons and protons in the universe is highlighted, and the mystery of their consistent charge is discussed. The quantization of charge is explained through the indivisible nature of protons and electrons. The professor also explains how charge transfer occurs in daily life, primarily through electrons, and how this understanding can explain phenomena like the attraction between charged rods.

The concept of polarization is introduced to explain how neutral objects can be attracted to charged objects. The professor discusses how charges within a neutral object can separate in response to a nearby charge, leading to a net attraction or repulsion. The difference between conductors and insulators is explained, and the importance of this distinction in everyday applications, such as avoiding electric shocks, is highlighted.

The professor outlines methods for verifying Coulomb's Law without relying on external definitions. Experiments involving varying distances between charges and using springs to measure force are suggested. The process of determining the amount of charge on a sphere by comparing it to a known standard charge is explained. The importance of considering how to measure physical quantities when conducting experiments and solving problems is emphasized.

The discussion turns to dark matter, explaining how its existence was inferred from discrepancies in gravitational calculations related to the rotation of galaxies. The professor highlights that while electric forces are significant, they can be neutralized, and thus, in cosmological calculations, gravity is the dominant force. The topic of how to experimentally determine the ratio of gravitational to electric forces is explored, and the importance of most objects being electrically neutral is noted.

The professor concludes with an example of calculating the electric force due to a continuous charge distribution, such as a charged ring. The concept of integrating the force over the charge distribution is introduced, and a specific calculation is performed to find the force on a charge placed near the ring. The importance of testing the result of such calculations is emphasized, with suggestions to verify the force behaves as expected in various scenarios.

The professor addresses the issue of students arriving late to class and provides preferences for which doors to use upon entering. A humorous warning is given against blocking the camera's view, emphasizing the importance of punctuality and proper classroom conduct.