This is the first in a series of chapters on electricity and magnetism. Much of it will be aimed at an introductory level suitable for first or second year students, or perhaps some parts may also be useful at high school level. Occasionally, as I feel inclined, I shall go a little bit further than an introductory level, though the text will not be enough for anyone pursuing electricity and magnetism in a third or fourth year honours class.
- All we have done so far is to define the potential difference between two points. We cannot define “the” potential at a point unless we arbitrarily assign some reference point as having a defined potential. It is not always necessary to do this, since we are often interested only in the potential differences between point, but in many circumstances it is customary to define the potential to be zero at an infinite distance from any charges of interest. We can then say what “the” potential is at s
- Electromagnetic induction occurs when a conductor placed in a changing magnetic field causes the production of a voltage across the conductor.
- Now is therefore quite a convenient time to gather together the various quantities we have come across, together with their dimensions (i.e. the powers of M, L, T and Q of which they are composed) and their SI units.
- We describe these four equations in this chapter, and, in passing, we also mention Poisson's and Laplace's equations. We also show how Maxwell's equations predict the existence of electromagnetic waves that travel at a speed of light. This is the speed at which light is measured to move, and one of the most important bases of our belief that light is an electromagnetic wave.
- The centimeter–gram–second system of units (CGS) is a variant of the metric system based on the centimeter as the unit of length, the gram as the unit of mass, and the second as the unit of time. All CGS mechanical units are unambiguously derived from these three base units, but there are several different ways of extending the CGS system to cover electromagnetism.