Fiona's
Database

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The way electricity is transported from power stations to sub-stations near populations.
This reduces the amount of energy lost in longdistance transmission.

The field can be viewed as the combination of an electric field and a magnetic field.
The electric field is produced by stationary charges, and the magnetic field by moving charges (currents);
these two are often described as the sources of the field.
Any device connected to an electrical outlet, even if the device is not switched on, will have an associated electric field.

ELF fields are defined as those having frequencies up to 300 Hz.
Emitted by power lines, electrical wiring and common appliances (e.g. electric blankets, televisions, hair-dryers, computers, etc.).
Naturally occurring ELF fields are associated with atmospheric processes such as ionospheric currents, thunderstorms and lightning.

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Used for telecommunications and heating food.
Able to pass through many things including human body.

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Radio waves, despite their name, are used for television transmissions

Terrestrial Trunked Radio (formerly known as Trans-European Trunked Radio).
TETRA was specifically designed for use by government agencies, emergency services, (police forces, fire departments, ambulance) for public safety networks, rail transportation staff for train radios, transport services and the military.
Used by countries in Western Europe, Eastern Europe, Middle East, Africa, Asia Pacific, Caribbean and Latin America.

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