Production of electricity :
Very large amounts of electrical energy lie dormant in the atoms of every speck of material in the universe. Whilst the atoms remain electrically balanced however, this electricity cannot be put to any practical use. What is needed is some form of external energy that will separate the electrons from their nuclei. In this way, the external energy that is applied will give rise to electrical energy.
There are six sources of external energy that are capable of separating the electrons from their nuclei, these are friction, pressure, magnetism, heat, light and chemical action.
Static electricity, that is the separation and build-up of charge is an everyday phenomenon that is often caused by friction - the physical stripping of electrons from one body and depositing on another. Early examples in science were the rubbing of a glass rod (which loses electrons and gains a positive charge) with a silk stocking! (gains electrons, receives negative charge) and the rubbing of an ebonite rod (receives negative charge) with cats fur (becomes positively charged). Everyday examples are:
• Combing the hair (dry). The comb attracts the individual hairs and the hairs repel each other and stand on end.• Removing a shirt (especially nylon). The shirt crackles and sparks may be seen, the shirt is also attracted to the body.• The receiving of ‘electric shock' from cars (also aircraft) when touching them on the outside. Here the charge has been produced by the friction of air passing around the vehicle.• The rapid collection of dust by records. The dust is attracted by the charge built up on the record produced by friction of handling and playing.• Lightning flash is a result of the build up of static electricity in clouds.• Although not used to produce electricity for any aircraft systems, static electricity is generated by friction as the aircraft moves through the air and will therefore be considered at various points throughout the course.