KALYAN CITY LIFE

What is a Semiconductor?

A semiconductor is a solid material that has electrical conductivity in between a conductor and an insulator; it can vary over that wide range either permanently or dynamically.

Semiconductors are important in electronic technology. Semiconductor devices, electronic components made of semiconductor materials, are essential in modern consumer electronics, including computers, mobile phones, and digital audio players. Silicon is used to create most semiconductors commercially, but dozens of other materials are used as well.

What are Semiconductor Devices?

Semiconductor devices are electronic components that exploit the electronic properties of semiconductor materials, principally silicon, germanium, and gallium arsenide. Semiconductor devices have replaced thermionic devices (vacuum tubes) in most applications. They use electronic conduction in the solid state as opposed to the gaseous state or thermionic emission in a high vacuum.

Semiconductor devices are manufactured both as single discrete devices and as integrated circuits (ICs), which consist of a number from a few to millions of devices manufactured and interconnected on a single semiconductor substrate.

What is Laser? Meaning

A laser is an optical device that emits coherent light (electromagnetic radiation). The term LASER is an acronym for Light Amplification by Stimulated Emission of Radiation.

Image credits © Fatllama

Typically, lasers are thought of as emitting light in a narrow, low-divergence beam, with a narrow wavelength spectrum (monochromatic light). Lasers need not have either characteristic, however, it is the coherence of the laser's output that is distinctive. Most other light sources emit incoherent light, which has a phase that varies randomly with time and position.

What is Genetically Modified (GM) Food?

Genetically modified (GM) foods, more accurately called Genetically Engineered Foods, are foods that have had their DNA altered through genetic engineering. Unlike conventional genetic modification that is carried out through conventional breeding and that have been consumed for thousands of years, GE foods were first put on the market in the early 1990s. The most common modified foods are derived from plants e.g. soybean, corn, canola, and cotton seed oil.

Controversies surrounding GM foods and crops commonly focus on human and environmental safety, labeling and consumer choice, intellectual property rights, ethics, food security, poverty reduction, and environmental conservation.

What is Nanotechnology? ↓

Nanotechnology refers to a field of applied science whose theme is the control of matter on an atomic and molecular scale. Generally nanotechnology is approximately 100 nanometers or smaller and involves developing materials or devices within that size. Nanotechnology is a highly multidisciplinary field, drawing from a number of fields such as applied physics, materials science, interface and colloid science, device physics, supramolecular chemistry, self-replicating machines and robotics, chemical engineering, mechanical engineering, biological engineering, and electrical engineering.

Image Credits © Picatinny Arsenal

Two main approaches are used in nanotechnology. In the 'bottom-up' approach, materials and devices are built from molecular components which assemble themselves chemically by principles of molecular recognition. In the 'top-down' approach, nano-objects are constructed from larger entities without atomic-level control. The impetus for nanotechnology comes from a renewed interest in Interface and Colloid Science, coupled with a new generation of analytical tools such as the atomic force microscope (AFM), and the scanning tunneling microscope (STM). Combined with refined processes such as electron beam lithography and molecular beam epitaxy, these instruments allow the deliberate manipulation of nanostructures, and lead to the observation of novel phenomena.

Examples of nanotechnology include the manufacture of polymers based on molecular structure and the design of computer chip layouts based on surface science. Despite the promise of nanotechnologies such as quantum dots and nanotubes, real commercial applications have mainly used the advantages of colloidal nanoparticles in bulk form, such as suntan lotion, cosmetics, protective coatings, drug delivery, and stain resistant clothing.

Inventions and Discoveries by Scientist - A to Z List

Adding Machine, 1642. Inventor : Blaise Pascal (France) (1623-62). Earliest commercial machine invented by William Burroughs (U.S.) in St. Louis, Missouri in 1885.

Addressograph, 1893. Inventor : J.S. Duncan (U.S.). Manufactured in Chicago, Illinois.

Airplane, 1903. Inventors: Orville Wright (1871-1948) and Wilbur Wright (1867-1912), (U.S.) Kitty Hawk, North Carolina.

Airship (non-rigid), 1852. Inventor : Henri Giffard (France) (1825-82). Steam-powered propeller flew over Paris (1852).

Airship (rigid), 1900. Inventor : Graf Ferdinand von Zeppelin (Germany) (1838- 1917). Bodensee.

Antiseptic, 1867. Inventor : Dr. Joseph Lister (England).

Arc Lamp, 1879. Inventor : C.F. Brush (U.S.) (1849-1929). Cleveland, Ohio.

Argon, 1894. Discoverers : Sir William Ramsay and Baron Ray Leigh (Great Britain).

Aspirin, 1899. Inventor : Dr. Felix Hoffman, Germany.

International System of Units SI

Sevres, France based International Bureau of Weights and Measures, serves as a depository for the primary international standards and as a laboratory for certification and intercomparison of national standard copies. In 1960, the SI system was built upon the MKS system, that is, metre-kilogram-second system, which has seven basic units. These are as follows :-

Metre (unit of length; Symbol m) defined as the distance travelled by light in a vacuum in 1/299,792,458 second;

Kilogram (unit of weight; Symbol kg) which equals 1,000 grams as defined by the international prototype kilogram of platinum-iridium in the keeping of the International Bureau of Weights and Measures;

Second (unit of time; Symbol s), the duration of 9,192,631,770 periods of radiation associated with a specified transition of the cesium-133 atom;

Ampere (unit of electric current; Symbol A), which is the current that, if maintained in two wires placed one metre apart in a vacuum, would -produce a force of 2 x 10^-7 Newton per metre of length;

Basic Physics Terminology For Science Students ↓

Absolute Zero or zero on the absolute temperature scale is the lowest temperature theoretically possible and is equal to -273.15°C or -459.67°F.

Adiabatic process is a process in which no heat enters or leaves a system. An adiabatic expansion results in cooling of a gas whereas an adiabatic compression has the opposite effect.