A colloidal system involving one liquid dispersed in another is known as emulsion. Any two immiscible liquids (those that cannot be mixed) can form an emulsion, like oil and water. An emulsifier is an agent that stabilizes the emulsion by lowering the interfacial tension between the constituents of the emulsion. Examples of emulsifiers are soaps, detergents and gelatine.

It is a device in the back of a “cathode ray tube” television or computer monitor (pre-plasma or LCD flat-panel). The electron gun fires a stream of electrons from the back of the TV onto the inside face of the screen, which is coated with a material that glows when hit by electrons. By using powerful magnets to direct the …

When a doctor takes a pulse he is feeling the patient’s heart-beat. If the heart is beating faster than normal it may be a sign like a rise in temperature of illness somewhere in the body. For signs of illness in the heart itself a more careful check is usually needed. The working of the heart is controlled by electrical …

An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving, physical components of the environment with which the organisms interact, such as air, soil, water and sunlight. It is all the organisms in a given area, along with the nonliving (abiotic) factors with which they interact; a biological …

An automatic car sounds as if it’s car that drives itself. In fact, it’s one in which the gears change automatically. The driver has to steer the car and operate the other controls such as the accelerator and brakes. The gear changes as the cars speeds up or slows down, and when it has to climb or descend a hill. …

The atomic pile is an early model of a nuclear reactor whose core consisted of layers of graphite blocks interspersed with uranium, designed to create a sustained fission reaction. The first atomic pile was created by Ernico Fermi and his colleagues at Columbia in 1942. It consisted of a stack of pure graphite bricks surrounding a neutron source. This first …

Corals are porous marine animals that live at the bottom of the ocean. Coral attaches to a strong foundation and then grows to create a coral reef. Corals are naturally vibrant and colourful. An artificial coral reef is a human-made underwater structure, typically built for the purpose of promoting marine life. Artificial reefs also improve hydrodynamics and help control beach …

An aqueduct is an artificial channel, usually an elevated one, for carrying water. The ancient Romans and Greeks were enthusiastic builders of aqueducts. Before the end of the first century A.D., Rome was supplied by nine aqueducts with a total length of more than 386 km, of which about 56 km were raised above ground.

The term AMOLED stands for Active Matrix Organic Light Emitting Diode/ Device/ Display. An Organic Light Emitting Diode (OLED), also Light Emitting Polymer (LEP) and Organic Electro Luminescence (OEL), is any Light Emitting Diode (LED) whose emissive electroluminescent layer is composed of a film of organic compounds. The layer usually contains a polymer substance that allows suitable organic compounds to …

An aMap (argument map) is a visual representation of the structure of an argument in informal logic. It includes the components of an argument such as a main contention, premises, co-premises, objections, rebuttals and lemmas. Argument maps are often used in the teaching of reasoning and critical thinking and can support the analysis of pros and cons when deliberating over …