It contains extra electrons. Putting these two thin P and N materials together produces a junction which, when exposed to light, will produce a movement of electrons - and that constitutes an electric current. Photovoltaic cells thus convert light energy into electrical energy. The theory that the Earth's surface is made up of huge plates that have moved very slowly during geological history, and continue to move, thus changing the position of continent and oceans. The plates are about 100 kilometres thick and move at a rate of about 1-12 centimetres per year.
Potential energy is stored or supressed energy.
For example, the wound-up spring of a toy has potential energy. In the example of the toy, potential energy is converted into kinetic energy when the toy is set running. A process which involves heating biomass to drive off the volatile matter, leaving behind the black residue we know as charcoal. The collected volatiles produce a gas rich in hydrogen and carbon monoxide. The Australian Foundation for Science and the Science and Technology Awareness Program of the Commonwealth Department of Industry, Science and Resources are also supporters of Nova .