Category: Science Dictionary

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.

Porous: Full of tiny pores that allow fluids or gasses to pass through.

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.

Nocturnal: Animals or insects that is active during the night and sleep during the day.

Natron: Natron is a natural salt, composed of sodium carbonate and sodium bicarbonate with traces of sodium chloride and sodium sulphate. It was used by the ancient Egyptians to dry out the bodies during mummification.

Mummification: The preserving of a dead body, by making it into a mummy.

Motion picture: Series of images on a strip of film usually projected at the rate of 24 frames per second, which make up a conceptually complete work. Also referred to as a film.

Morse Code: A telegraph code in which letters and numbers are represented by strings of dots and dashes (short and long signals)

Mordant: Any substance used to facilitate the fixing of a dye to a fibre

Momentum: Momentum is the product of the mass and velocity (speed) of an object (p = mv).

Mold: A fungus that produces a superficial growth on various kinds of damp or decaying organic matter.

Milliammeter: A sensitive ammeter for detecting small currents, graduated in milliamperes.

Microbes: Minute living organisms, including but not limited to bacteria, viruses and fungi.

Michael Faraday: Michael Faraday was a British physicist and chemist, best known for his discoveries of electromagnetic induction and of the laws of electrolysis. Born in 1791, Faraday was the son of a blacksmith and received little formal education. While working for a bookbinder in London, he read many scientific books and experimented with electricity. Faraday’s most important scientific contributions were in the fields of electricity and magnetism. In 1821 Faraday plotted the magnetic field around a conductor carrying an electric current, and in 1831 he followed this accomplishment with the discovery of electromagnetic induction.

Methylene blue: A blue dye used as a stain, an antiseptic, or a chemical indicator. Methylene blue has many uses in a range of different fields, such as biology and chemistry.

Metamorphic rock: Rocks formed from other rocks under pressure and extreme heat.

Metals: Any of several chemical elements that are usually shiny solids that conduct heat or electricity and can be formed into sheets. Most metals also have magnetic properties.

Metabolism: The chemical reactions that allow organisms to grow and reproduce, maintain their structures, and respond to their environments. Metabolism is usually synonymous with energy production.

Meniscus: The curved top of a column of liquid, such as ‘water’ in a small tube. It is formed because the attractive forces between the tube and the water molecules (adhesive forces) are stronger than the cohesive forces between individual water molecules.

Membrane: A pliable sheet of tissue that covers or lines or connects the organs or cells of animals or plants.

Mealworms: Mealworms are the larva form of the mealworm beetle, ‘Tenebrio molitor’, a species of darkling beetle. Like all holo-metabolic insects, they go through four life-stages: egg, larva, pupa, and adult. Mealworms are a tasty treat for hamsters.

Matter: Matter is a general term for the “stuff” of which the world is made.

Mantle: Earth’s mantle is a rocky shell about 2,890 km thick that constitutes about 84 percent of Earth’s volume. It is predominantly solid and encloses the iron-rich hot core, which occupies about 15 percent of Earth’s volume.

Maltose: A white crystalline sugar formed during the digestion of starches.

Male ants: Male ants do not work and live only a few weeks or months. The only purpose of the male ant is to mate with the queens and they die shortly thereafter.

Magnification: A measurable increase in the apparent size of an object. This enlargement is quantified by a calculated number also called ‘magnification’. Magnification is the ratio between the apparent size and the true size of the viewed object behind the lens or other magnifier.

Magnetism: The force of attraction or repulsion of a magnetic material due to the arrangement of its atom. A magnet is a metal object that attracts pieces of ferrous (metal) objects.

Magnetic North: North according to the Earth’s magnetic poles rather than its geographic poles. Declination from true north is given in miles where one mile equals 1/6,400 of 360 degrees.

Magnetic field: A condition in the space around a magnet or electric current in which there is a detectable magnetic force and two magnetic poles are present.

Machine: Any mechanical or electrical device that transmits or modifies energy to perform or assist in the performance of human tasks. Also, a device that has parts to perform or assist in performing any type of work.

Lye: Lye is a strong alkaline substance, commonly ‘sodium hydroxide’ or ‘caustic soda’ (NaOH)

Lunar month: The average time between successive new or full moons. A lunar month is equal to 29 days 12 hours 44 minutes. Also called a ‘synodic’ month.

Lumens: The SI unit of luminous flux. It is a measure of the power of light that can be perceived by the human eye.

Logic gate: A computer circuit with several inputs but only one output that can be activated by particular combinations of inputs

Little dipper: A cluster of seven stars in the constellation Ursa Minor also called Little Bear. At the end of the dipper’s handle is ‘Polaris’, the North Star.

Litmus: A colouring material (obtained from lichens, a composite organism consisting of fungi) that turns red in acid solutions and blue in alkaline solutions. It is used as a very rough acid-base indicator.

Lignum: Wooden tissue. This may or may not contain the bark of the tree as well.

Lift: A fluid flowing past the surface of a body exerts a surface force on it. Lift is defined to be the component of this force that is perpendicular to the oncoming flow direction. Lift Take off or away by decreasing the air pressure.

Lever: A rigid bar used to apply pressure at one point along its length by applying a force (effort) at a second point and turning about a third point or fulcrum.

Leonardo da Vinci: Leonardo da Vinci, born in 1452, is considered as perhaps the most diversely talented person ever to have lived. Primarily known as an artist for his paintings and sculpting, he was also a scientist, mathematician, engineer, inventor, musician, writer and architect and was recognized in many more fields! It is even rumoured that he could paint with one hand and write with the other at the same time. Although relatively few of his designs were constructed or were even feasible during his lifetime, Leonardo is praised for his technological ingenuity. He conceptualised a helicopter, a tank, concentrated solar power, a calculator and many, many more during his lifetime!

Landslide: A rapid down slope mass movement where water in the soil and rock has accumulated to sufficiently increase stress and lubricate bedding planes.

Knee-jerk reaction: The involuntary contraction of the leg when the knee is tapped with a doctor’s mallet.

Kinetic energy: The energy possessed by an object by virtue of its motion is called kinetic energy.  The greater the mass or speed of the object, the greater is the kinetic energy.  Kinetic means active or moving.  Kinetic energy can be defined as energy in motion or the energy of a moving object.

Kilowatt hour: A kilowatt-hour (kWh) is a standard metric unit of measurement for electricity consumption for billing purposes. It can simply be described as 1000 watts of electricity used for one hour.

Kelvin: Kelvin is the fundamental unit of temperature adopted under the Systeme International d’Unites (SI).  It is not calibrated in terms of the freezing and boiling points of water, but in terms of energy itself.  The number 0 K is assigned to the lowest possible temperature, called ‘absolute zero’.

Kazoo: A toy wind instrument that has a membrane that makes a sound when you hum into the mouthpiece.

Kaleidoscope: A tubular instrument containing loose bits of coloured glass, plastic, etc. reflected by mirrors so that various symmetrical patterns appear when the tube is held to the eye and is rotated

Jean Foucault: Jean Bernard Léon Foucault (18 September 1819 – 11 February 1868) was a French physicist best known for the invention of the Foucault pendulum, a device demonstrating the effect of the Earth’s rotation.

Isaac Newton: Sir Isaac Newton (1642-1727), a mathematician and physicist were of the foremost scientific intellects of all time and who is famous for his ‘action-reaction law’ which states: ‘to every action there is an equal and opposite reaction’

Iron: A metallic chemical element with the symbol ‘Fe’ and atomic number 26.

Iris: A muscular diaphragm that controls the size of the pupil which in turn controls the amount of light that enters the eye. The iris forms the coloured portion of the eye.

Iodine: A non-metallic element belonging to the halogens. Iodine is used especially in medicine and photography and in dyes. It occurs naturally only in combination in small quantities as in sea water or rocks.

Invisible ink: A substance used for writing, which is invisible either on application or soon thereafter, and which can later on be made visible by some means.

Integrated circuit: A collection of active and passive electrical components such as transistors and resistors mounted on a single slice of silicon and packaged as a single component. An integrated circuit is also known as an IC, microcircuit, or microchip.

Insulator: A material such as glass or porcelain with a very tiny electrical or thermal conductivity.