Models help us understand processes we can't visualize. Light has two primary models or theories, the particle theory and the wave theory. Newton believed in the particle theory, while Huygens was a wave theory proponent. The destructive and constructive interference patterns shown by Young's double slit experiment reinforced the wave model. Maxwell proposed that light is an electromagnetic wave, part of the EM spectrum. Hertz produced radio waves as part of the EM spectrum. It seems like wave theory had the edge, until Einstein and his quantum theory of light.

We discussed how electromagnetic waves are produced by a moving electric charge producing a magnetic field, and a moving magnetic field producing an electric field. The structure of the EM wave was seen by image, with the electric, magnetic, and direction all perpendicular to each other. The wave formula was shown to exist for these waves as well as sound and light, and the speed shown to always be equal to the speed of light. The term dielectric was discussed and the dielectric constant explained and given for a few common substances. The velocity of the EM wave through differing conductors was determined by the formula V=speed of light/square root of the dielectric constant. A few problems from the text were solved.

Faraday's law was restated as an introduction to how transformers work. The physics of the transformer progressed from two coils of wire next to each other, with current passing through one of them to the modern transformer with wire coils around arms of an iron square. The step down and step up transformers were viewed in images, showing the difference in wire loops between the primary and secondary coils, causing the voltage difference by induction.

Discuss how resistance to the current flow can occur in a conductor. The thickness and diameter of the wire, as well as the temperature will affect the flow. Show that the unit of measurement of resistance is the Ohm, which is determined in a circuit by using Ohms law. The law states that the voltage is related to the current and the resistance. V=IR. Also point out that the current is directly related to the voltage and inversely related to the resistance. Solve a few textbook problems using Ohms law.

The production of an electric current by electromagnetic induction will be reviewed, as well as production of a magnetic field by moving charges. Faraday's law will be restated. From electromagnetic induction, the production of an electromagnetic wave will be discussed, along with an image of the wave, its electric and magnetic parts, and the direction of movement. How a radio wave is produced and received will be shown.

Review electric potential energy/charge and volts. Discuss voltage sources and potential difference. Determine that the amount of charge that flows through a circuit depends on voltage and resistance. Discuss resistance, what causes resistance, and how resistance differs due to thickness and temperature of the conducting wire. The unit of resistance is the Ohm.

The flow of water in a stream was used to demonstrate that water will flow from a higher level to a lower level. In order to keep a continuous flow of water in a fountain, a pump must be used to lift the water back to a higher level. Electric charge will flow when there is a difference in electric potential from one end of a conductor to another. This flow will continue until there is no potential difference between the ends of the conductor. As long as there is a potential difference, electrons will flow (current). Conduction electrons were explained and reinforced by a short video. The measurement of flow was discussed as coulombs/sec passing a point, and the unit was called the ampere, or amp or just shown as A. 1A = 1C/s.

Review of potential energy and electrical potential energy... Electrical potential energy is the energy a charge has due to its position in an electric field.. The difference in electrical potential energy and electric potential was restated and shown to be the total electrical p.e./amount of charge. It is joules/coulomb and measured in units called volts. The electric potential is called voltage. What a capacitor is, and how it works, and how it differs from a battery was discussed and a short video was used to demonstrate its uses and explain how it is charged. How a difference in voltage will affect the brightness of a bulb was also shown, and explained in terms of electrons /sec passing through the bulb.

A review of potential energy and kinetic energy was developed to lead into electrical potential energy. The use of work to move an object in the direction of the force applied, and that when the object is moved a certain distance from the surface, the potential energy is the gravitational potential energy. The is determined by the mass, the acceleration due to gravity, and the distance moved. The electrical potential energy is the potential energy a charged object can have by virtue of its location in an electric field. Work is done to push a single charge against the electric field, the more work done the greater the potential energy.This is compared to the electric potential, which is the electric potential energy per unit charge. The unit of electric potential is the volt, which is joules/coulomb.

Magnetism can produce electricity and electricity can produce magnetism. Working from this statement, how this comes about was examined. It was shown that electric current can be produced in a wire by moving a magnetic field in and out of a loop of wire. The key is the field must be moving. The reverse procedure also will produce a current, moving the loop through the magnetic field. A short video was used to show this effect. The factors which influence the magnitude of the voltage was introduced along with Faraday's law. What a generator is, and how it produces current, was examined and then seen in a short video showing a hand generator and the production of current. Textbook questions were given to be answered by next Tuesday, as a test.