Most storage devices that do not require vision and a brain to read data fall into this category. Electromagnetic data may be stored in either an analog data or digital data format on a variety of media.
Direct Tripwire Alarm - The wire placed across the path is directly connected with the cord, wire or string placed across the particular path. Laser Tripwire Alarm - An invisible laser, typically an infra-red, is used instead of a cord or string.
The wire that is connected to ground pin of a plug is connected to the metal body of the equipment. Any leakage current appearing on the metal body of the equipment must be discharged safely to ground so the user (You) do not get any electric shock when using the equipment.