ACCA, MBA, Tax Agent ជាអ្នកនិពន្ធហើយអាចប្រលងជាប់៖ ACCA រហូត ៤ មុខវិជ្ជាក្នុងពេលតែម្តង, Tax Agent ពិន្ទុខ្ពស់, MBA & BBA ជាប់ជាសិស្សពូកែ និងមានបទពិសោធការងារជាង ១៥ ឆ្នាំ ព្រមទាំងអ្នកនិពន្ធផ្សេងៗ ?ទិញឯកសារហើយ អានមិនយល់អាចសួរបាន
Sheet erosion: Relatively even erosion of a layer of soil without channel formation and generally takes place on sloping land.
Shadow clock: An ancient time telling device consisting of a straight base with a raised crosspiece at one end, which uses the length of the sun’s shadows because of its position, in relation to a specific location on earth, to tell the time.
Semi-permeable: It allows certain things to pass through while blocking others.
Seismograph: A device that is used to accurately record the motion of the ground during an earthquake.
Scurvy: A deficiency of ‘Vitamin C’. Symptoms include nausea, weakness, loss of hair and teeth, and eventual death. It is caused by a lack of fruits and vegetables in the diet. More sailors at sea died of this than any other cause.
Saturated: A ‘saturated’ solution is the most concentrated solution possible at a given temperature. The solution is unable to dissolve still more of a specific substance.
Samuel Morse: Samuel Finley Breeze Morse was born in Charlestown, Mass. on 27th April 1791. He was a professional artist, inventor of the electric telegraph and the originator of ‘Morse’ Code. Morse is remembered for his Code, still used, and less for the invention that enabled it to be used, probably since landline telegraphy eventually gave way to wireless telegraphy.
Salivary gland: Any of three pairs of glands in the mouth and digestive system that secrete saliva for food digestion.
Saliva: Saliva, also known as spit, or slobber, is the watery substance produced in the mouths of humans and most other animals by the salivary glands. The saliva moistens the mouth and starts the digestion of starches in the mouth.
Rust: A red or brown oxide coating on iron or steel caused by the action of oxygen and moisture. Rusting is the common term for the ‘corrosion’ or the disintegration of a material into its constituent atoms, due to chemical reactions with its surroundings.
Rudder: A rudder is a device (vane) used to steer a ship, boat, submarine, hovercraft, aircraft, or other vessel that moves through a fluid (generally air or water).
Rotor: A rotating mechanism, consisting of an assembly of rotating airfoils, that extracts energy from a fluid or air flow and converts it into useful work.
Richter scale: A logarithmic scale, invented in 1935 by United States geophysicist Charles Richter, for representing the energy released by earthquakes. A figure of 2 or less is barely perceptible, whereas an earthquake measuring over 5 may be destructive, and 8 or more is a major earthquake.
Rheostat: An electrical resistor, with two terminals, whose resistance are continuously variable by moving a knob or slider and correspondingly decrease or increase the current flowing.
Retina: A delicate, multilayered, light-sensitive membrane lining the inner eyeball and connected by the optic nerve to the brain.
Respiration: Respiration (or just breathing) is defined as the transport of oxygen from the outside air to the cells within tissues, and the transport of carbon dioxide in the opposite direction.
Relay: A mechanical relay is an electromechanical device that closes contacts to complete a circuit or opens contacts to interrupt a circuit. A solid state relay is a switching device that completes or interrupts a circuit electrically and has no moving parts.
Relative humidity: This is the ratio of the amount of water in the air at a given temperature to the maximum amount it could hold at that temperature. Relative humidity is expressed as a percentage.
Refraction: The change in direction of a propagating wave (light or sound) when passing from one medium to another
Refracting telescope: A telescope in which a large biconvex lens causes light rays to converge to a focus, forming an image magnified by a biconvex eyepiece. A telescope is a device used to magnify distant objects.
Rayleigh scattering: The elastic scattering of light or other electromagnetic radiation by particles much smaller than the wavelength of the light. Named after English physicist Lord Rayleigh.
Rain gauge: An instrument meteorologists use to measure the amount of rainfall.
Radio: An electronic receiver that detects and demodulates and amplifies transmitted signals.
Radiation: The act or process of radiating; the radiation of heat and light from a fire.
Queen ants: The queen ant is the only ant that is capable of laying eggs and this is also her main role in an ant colony. She is brought food and is cleaned by workers ants and they also tend to the eggs that she lays. The queen ants do not make any decisions about the colony, the decisions are carried out by the entire colony.
PV (Photovoltaic) Panels: Man-made cells that are comprised of semiconductors, materials that are able to absorb light energy, arranged in a panel form to produce electric power
Pulse: The rhythmic contraction and expansion of the arteries with each beat of the heart.
Pulley system: A simple machine, consisting of a wheel with a groove in which a rope can run to change the direction, or point of application of a force applied to the rope
Protractor: An instrument for measuring or drawing angles on paper, usually a flat semicircular transparent plastic sheet graduated in degrees
Protein: Any of the ‘amino acids’ present in all living matter that are an essential food item.
Propulsion: A force causing movement.
Proprioception: The ability of living organisms to sense the position and location and orientation and movement of the body and its parts.
Proportion: A special type of ratio expressing a relationship between the part and the whole.
Prism: A transparent body of this form, often of glass and usually with triangular ends, used for separating white light passed through it into a spectrum or for reflecting beams of light.
Pressure: The force applied to a unit area of surface often measured in pascals (SI unit) eg. “the compressed gas exerts an increased pressure”. Pressure = Force / Area
Preservatives: A preservative is a natural or synthetic substance or chemical that is added to products such as foods, pharmaceuticals, paints, biological samples, wood, etc. to prevent decomposition by bacterial growth or by unwanted chemical changes.
Potential energy: The energy possessed by an object because of its position (for instance with regards to gravitational force or in an electric field), or its condition (for instance a stretched rubber band)
Potassium nitrate (Saltpetre): KNO3 is a naturally occurring mineral source of nitrogen. Its common names include saltpetre or nitrate of potash. It is used in the production of nitric acid, model rocket propellants, and several types of fireworks.
Potassium iodide: A white crystalline salt used in making photographic emulsions and in iodized table salt. Potassium iodide is an inorganic compound with formula KI.
Polymer: A long or larger molecule consisting of a chain or network of many repeating units, formed by chemically bonding together many identical or similar small molecules called ‘monomers’.
Polaris: The brightest star in Ursa Minor located at the end of the handle of the Little Dipper. The northern axis of the earth points almost directly toward it making it the current northern pole star. Polaris has gone by so many names in its past: North Star, Steering Star, Lodestar, Stella Mars and the Ship Star.
Plateau: A plateau is also called a ‘high plain’ or ‘tableland’. It is an area of highland, usually consisting of relatively flat terrain. A highly eroded plateau is called a dissected plateau.
Plastron: The plastron is the nearly flat part of the shell structure of a turtle or tortoise, what one would call the belly
Pitch: The property of sound that varies with variation in the frequency of vibration.
Pigment: A substance whose presence in plant or animal tissues produces a characteristic colour.
Phototropism: The tendency of plans to move or grow towards light.
Photosynthesis: The process that enables plants and some bacteria to capture the sun’s energy and turn it into food and oxygen.
Persistence of vision: A visual phenomenon where an image is retained in the eye for a short period of time, creating an illusion of continuous motion in film and video.
Pheromones: A chemical substance secreted externally by some animals, especially insects, which influences the physiology or behaviour of other animals or insects of the same species.
Permeability: A measure of the ability of a porous material such as the walls or membranes of cells to transmit fluids.
Periscope: An instrument that has angled mirrors or prisms and allows objects not in the direct line of sight, to be seen. It is often used on submarines and in the military.
Periodic table: A tabular arrangement of the chemical elements according to atomic number as based on the periodic law.
Perimeter: A perimeter is a path that surrounds an area or an object.
Perfume: A pleasant smell, scent or odoriferous particles emitted from a sweet-smelling substance.
Pendulum: A weight suspended from a pivot so it can swing freely.
Pedestal: A base, a support or a foundation.
Pascal’s principle: States that: Pressure applied to an enclosed fluid is transmitted undiminished to every part of the fluid, as well as to the walls of the container.
Partial melting zone: The layer between the crust and the mantle of the earth. This layer consists of a molten rock ‘liquid’ with high viscosity and acts like a viscous ‘sea’ upon which the continents drift!
Papier-mâché: A substance made from paper pulp that can be moulded when wet and painted when dry.
Paper Chromatography: An analytical chemistry technique for separating and identifying mixtures that are or can be coloured, especially pigments. This can also be used in secondary or primary colours in ink experiments.
Pangaea: A hypothetical continent including all the landmass of the earth prior to the Triassic period when it split into Laurasia and Gondwanaland.
Oxygen: Oxygen, scientifically known as O2, occupies about 21 percent of the earth’s atmosphere and is also found in other substances including water. It can combine with many other elements and it is essential for plants & animals to breathe. Oxygen is also required for nearly all combustion.
Oxidation: The addition of oxygen to a compound accompanied with a loss of electrons
Osmosis: Osmosis is the diffusion of a liquid through a cell wall or membrane. Osmosis is the means by which water and nutrients move.
Oscilloscope: An electronic device with a screen, which displays a picture of the voltage of an electrical signal. When this device is connected to the output of an audio amplifier, it displays patterns related to the sound pressure coming out of the loudspeaker.
Oscillator: A tuned electronic circuit used to generate a continuous output repetitive variation, typically in time.
Optician: A specialist in fitting eyeglasses and making lenses to correct vision.
Optical illusion: An optical phenomenon that results in a false or deceptive visual impression.
Optic nerve: The optic nerve transmits visual information from the retina to the brain.
Oil: Any of a group of fats that is a liquid at room temperature that are obtained from plants.
Mycology: The branch of living sciences concerned with the study of fungi.
Ohm’s law: Ohm’s law states that the current through a conductor between two points is directly proportional to the potential difference or voltage across the two points, and in reverse proportional to the resistance between them.
Non-ferrous metals: Non-ferrous metals are those that have very little iron content. Non-ferrous metals are non-magnetic metals such as gold, silver or aluminium.