Electrical fields

Students will have first come into everyday contact with electric field phenomena when seeing a rubbed balloon stuck to a wall, or, on a much grander scale, through lightning. They may have been told of many other applications of electric fields in areas such as photocopying, laser-printing, flue-ash precipitation, spray-painting etc.

They will now study the field in more detail, following much the same route as with the gravitational field (although there is naturally more practical work that can be included with E-fields than with g-fields). In fact, from the beginning the similarities between g-fields and E-fields should be brought out – in particular the fact that they are both inverse square laws, and so their equations look very similar indeed. The only major differences are that with E-fields we deal with repulsions as well as attractions, and that the strength of the electric force between two point charges is gargantuan compared to the gravitational force between them.