2.07 Resistance

We have now established the fact that electrical current is the rate of flow of charged particles (usually electrons) in an electrical circuit. Devices such as batteries which power electrical circuits possess an electromotive force (e.m.f.). The e.m.f increases the electrical potential (the energy per unit of charge) of the electrons at the negative terminal of the battery. If a conductive circuit is connected between the terminals of the battery the electrons will be attracted towards the positive terminal. As they travel towards the positive terminal the electrical potential of the electrons is reduced as they dissipate the energy which was supplied by the e.m.f. In this section we will explain how this energy is dissipated. The energy is dissipated due to a property called electrical resistance. Resistance converts electrical energy to heat energy.

Drude's model of resistance

As the electrons move through the conductors they collide with molecules in the material loosing energy in the process. This energy is transferred to the molecules causing them to vibrate and therefore raising the temperature of the material. The heat energy is then dissipated into the environment.

drudes model of resistance