Disposal of waste: This waste includes sewage, garbage and liquid waste from factories and homes. Wastages from chemical factories contain many toxic or poisonous chemicals. These are discharged into rivers. The river-water becomes poisonous for fish and other aquatic animals and plants.
Proximity. Proximity describes the tendency to perceive objects that are close to one another as being grouped together in a meaningful way. For example, you are likely to perceive no groupings in the following series of equally spaced squares:roximity. Proximity describes the tendency to perceive objects that are close to one another as being grouped together in a meaningful way. For example, you are likely to perceive no groupings in the following series of equally spaced squares:
Infrared proximity sensor. A proximity sensor is a sensor able to detect the presence of nearby objects without any physical contact. A proximity sensor often emits an electromagnetic field or a beam of electromagnetic radiation (infrared, for instance), and looks for changes in the field or return signal. The object being sensed is often referred to as the proximity sensor's target. Different proximity sensor targets demand different sensors. For example, a capacitive or photoelectric sensor might be suitable for a plastic target; an inductive proximity sensor always requires a metal target.