Â­TÂ­here are many different ways to create a motion sensor. For example: 1  It is common for stores to have a beam of light crossing the room near the door, and a photosensor on the other side of the Â­room. 2  When a customer breaks the beam, the photosensor detects the change in the amount of light and rings a bell.
Effluent is an outflowing of water or gas from a natural body of water, or from a manmade structure. Effluent, in engineering, is the stream exiting a chemical reactor. Effluent is defined by the United States Environmental Protection Agency as wastewater - treated or untreated - that flows out of a treatment plant, sewer, or industrial outfall. Generally refers to wastes discharged into surface waters.
What is the difference between a dam, a weir and a barrage? A weir is an impervious barrier constructed across a river to raise the water level on the upstream side. The water is raised up to the required height and the water then flows over the weir. In a weir the water overflows the weir, but in a dam the water overflows through a special place called a spillway. Weirs have traditionally been used to create mill ponds.