Welcome to the Rossini College electronic series of videos. This video will be about the discovery in early history of electricity and introducing some fundamental concepts. In about 600 BC the Greeks realized that Amber, which is fossilized tree sap, had some interesting properties. It could make our hair stand up on end and pick up some light objects or in a generator spark if rubbed in a certain way. Here is an example of a very large spark caused by the same phenomenon that we now know as static electricity. It wasn't until the late 19th century that we started to really understand what was behind these phenomena. JJ Thompson theorized that an atom consisted of two types of particle, one positively charged and the other negatively charged. These were spread evenly throughout the atom in what is known as the plum pudding model. Anus Rutherford later performed experiments that showed this to be inaccurate, beginning the development of the orbital model of the atom with a very small positively charged and heavy nucleus and with negatively charged and light particles called electrons in orbits around it. This is further developed by Niels Bohr in the early 20th century, paving the way to our modern understanding of the atom. Here is a much simplified diagram showing this. Charges are difficult concept to describe well. However, it can be said that any charged particles will feel the force of attraction or repulsion to another charged particle. Some charges repel whereas some charges repel whereas opposite charges attract. Charged particles have an electric field associated with them and more formally it is the interaction of these fields that provide the forces we see. Magnetism is also related to charged particles and we will explore this further in another video. An electric current is where charged particles are moving. In metals it is the electrons that move. Metals are different than non-metals because some of the electrons in each atom become dissociated. This means that these electrons do not belong to any one particular atom rather they are shared between all metal atoms in their particular piece of metal. They are known as D localised electrons and provide the metal with many of its properties such as Luster or the shiny metallic look that we see. Malleability which is ability to be bent or shaped without breaking or its ability and more importantly for us it can conduct electricity as a solid. If a particle with the excess charged is placed near a metal the electrons are repelled or attracted depending on which charge it is and move accordingly. This has the effect of containing the electric field associated with that particle allowing us to use it. If electrons are continuously moving as in a circuit we have an electric current you can think of it in similar terms to water moving in a hose. I will be using the water analogy quite often to describe electricity concepts however it should be noted that it does not always explain the whole story. Next video I'll be looking at basic circuits and what current voltage and resistance means in that context.