Ground loop (electricity)

In an electrical system, a ground loop or earth loop is an equipment and wiring configuration in which there are multiple paths for electricity to flow to ground. The multiple paths form a loop which can pick up stray current through electromagnetic induction which results in unwanted current in a conductor connecting two points that are supposed to be at the same electric potential, often, but are actually at different potentials.

Ground loops are a major cause of noise, hum, and interference in audio, video, and computer systems. They do not in themselves create an electric shock hazard, however the inappropriate connections that cause a ground loop often result in poor electrical bonding, which is explicitly required by safety regulations in certain circumstances. In any case the voltage difference between the ground terminals of each item of equipment is small. A severe risk of electric shock occurs when equipment grounds are improperly removed in an attempt to cure the problems thought to be caused by ground loops.

Project Earth (TV series)

Project Earth is a 2008 reality TV series on the Discovery Channel in which several groups of scientists experiment with radical ideas to slow and/or stop global warming using geoengineering methods.

Projects

The show consists of eight experiments to weigh pros and cons of ideas on how to reduce global warming. The projects are as follows:

Wrapping Greenland

Seeing if glacier melting on Greenland can be prevented by covering them with insulating sheets.

Raining Forests

Led by scientist Mark Hodges, they attempt to reforest areas of bare Earth from helicopters using canisters holding a tree seedling.

Brighter Earth

Led by atmospheric physicist John Latham and engineer Stephen Salter, the team attempted a Cloud reflectivity enhancement experiment. Their goal was to make clouds more reflective to bounce more of the Sun's heat generating rays back into space as a stop-gap against global warming. By changing the size of water droplets within a cloud, they make clouds brighter and reflect the Sun's heat into space. They choose to seed marine stratocumulus clouds because of their commonality around the world and the fact that they are low-lying, making it easier for man-made droplets to reach them. The Project Earth team uses the potassium chloride and sodium chloride from (salt-based) flares to form droplet particles that are one micrometre in diameter, and that can rise to 300 ft (91 m), even in adverse (cloudless) conditions. The experiment proves that man-made droplets can indeed seed stratocumulus clouds.