What is Electromagnetism?
[[File:Electromagnitivity Difference.svg|thumb|A graph showing the differences in Electromagnetism]] '''Electromagnetism''' is one of the four [[Fundamental force|fundamental forces]] of nature. The others are [[gravity]], and the [[Strong interaction|strong]] and [[weak interaction]]s of [[particle physics]].<ref>A. Beiser (1987). Concepts of Modern Physics (4th ed.). McGraw-Hill (International). ISBN 978-0-07-100144-1</ref> The electromagnetic force pushes or pulls anything that has an [[electric charge]], like [[electrons]] and [[protons]]. It includes the [[Electricity|electric]] force, which pushes all charged particles, and the [[Magnetic field|magnetic]] force, which only pushes moving charges. There are two types of electric charge: positive and negative. The electric force pulls opposite charges (positive and negative) towards each other. It pushes similar charges (both positive, or both negative) away from each other.<ref>L.H. Greenberg (1978). Physics with Modern Applications. Holt-Saunders International W.B. Saunders and Co. ISBN 978-0-7216-4247-5</ref> == What is a field? == The electromagnetic force comes from something called an electromagnetic field. In physics, a field is how we keep track of things that might change in space and time. It is like a set of labels for every point in space. For instance, the air temperature in a room could be described by a field, where the labels are just numbers saying how hot it is at that point in the room. We could have more complicated labels as well. On a map of wind speeds, the label could be a number saying how strong the wind is and also an arrow saying which way it is blowing. We call this a [[vector field]] because each label is a vector - it has a direction (the arrow) and a magnitude (its strength).<ref>P.M. Whelan; M.J. Hodgeson (1978). Essential Principles of Physics (2nd ed.). John Murray. ISBN 978-0-7195-3382-2</ref> Electric and magnetic fields are also fields. Instead of keeping track of temperature or wind speed, they tell us how much push o