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Science Glossary

What exactly does the terms mean?


Glossary - A


Any water-soluble compound having a sour taste and capable of turning litmus red and reacting with a base to form a salt. Acid has a pH-level of less than 7.0 (A pH of 7 is neutral).

Acid rain

Rain which is unusually acidic (pH of less than the natural range of 5 to 6), caused mainly by atmospheric pollution with sulphur dioxide and nitrogen compounds.


A mixture of gases (especially oxygen) required for breathing; the stuff that the atmosphere consists of.

Air pressure (Atmospheric pressure)

Air pressure is the weight of the atmosphere pressing down on the earth. It is measured by a barometer in units called millibars.

Albert Einstein

Albert Einstein (14 March 1879 – 18 April 1955) was born in Germany and was a Jewish philosopher and author, who is widely regarded as one of the most influential and best known scientists and intellectuals of all time. In 1933, he joined the Institute for Advanced Study in Princeton, New Jersey and lived and worked there until his death. Einstein is probably familiar to most people for his mathematical equation about the nature of energy, E = MC2.


Relating to or containing an alkali, hence having a pH greater than 7. Alkaline batteries have potassium hydroxide as its electrolyte and a zinc / manganese dioxide cell.


The height above sea level or above the earth’s surface.


A sperm whale secretion. Sperm whales produce it to protect their stomachs from the beaks of the cuttlefish they swallow, and formerly valued greatly in the manufacturing process of perfumes.

Ambient Temperature

The temperature of the surrounding air.


An electronic device that changes, usually increases, the strength or amplitude of a signal passing through it.


To make larger or more powerful; increase.


To increase the volume of or ‘amplify’ sound.


An anemometer is a meteorological instrument that measures wind speed, either be gauging velocity or pressure.


An ancient circular instrument used to observe and calculate the position of celestial bodies.


The gases surrounding the Earth or any astronomical body of sufficient mass, held together by the gravity of the body.


The smallest component of an element or ‘matter’ having the chemical properties of the element.

Glossary - B


Very small living organisms made of only one cell which are present everywhere (the air, the soil, on the skin). Many types of bacteria can cause diseases, but others can be very helpful to humans.


A state of equilibrium

Balance point

The point along the length of the shaft at which it will balance itself when placed on a fulcrum.


An instrument for measuring atmospheric pressure, used especially in weather forecasting, but is also used to measure altitude.


The point at the centre of a system; an average point, weighted according to mass or other attribute.


The opposite of an acid. A Base has a pH-level of more than 7.0 up to 14.0 (A pH of 7 is neutral)

Benjamin Franklin

Benjamin Franklin, (January 17, 1706 – April 17, 1790) was one of the Founding Fathers of the United States of America. Franklin was a leading author and printer, satirist, political theorist, politician, scientist, inventor, civic activist, statesman, and diplomat. As a scientist, he was a major figure in the Enlightenment and the history of physics for his discoveries and theories regarding electricity.

Berlese funnel

A device in which soil is placed; heat and light are applied from above, forcing bugs into a container below it. Named after Antonio Berlese an Italian entomologist.

Bernoulli’s principle

The principle of conservation of energy applied to fluid flow: as the speed of a moving fluid increases, the air pressure within the fluid decreases. Named after Daniel Bernoulli, a Swiss mathematician and scientist, Bernoulli is famous for his work in the field of fluid dynamics. In 1738 he wrote a book called Hydrodynamica. In this book he explained his theories about how gases and fluids move, and how the speed at which they move affects the pressure they exert on objects they flow around.


The biceps of a human is a muscle located on the upper arm. The biceps has several functions, the most important being to rotate the forearm and to flex the elbow.

Big dipper

A group of seven bright stars in the northern sky, near the pole – also called the constellation Ursa Major or the Great Bear.

Binary code

Electronic data used in computers. The circuit is either on or off and is represented with either a 1 or 0. The system uses the digits 0 and 1 to represent a letter, numeral or other character in a computer.

Binaural hearing

The perception of sound by stimulation of two ears affecting a listener’s ability to identify the location or origin of a detected sound in direction and distance.


A ‘biosphere’, also called an ‘ecospheres’, is a mostly closed ecosystem of a specific size that contains a mix of plants and animals that is completely self-sufficient.

Block and tackle

A block and tackle is a compound pulley where several pulleys are mounted on each axle, further increasing the mechanical advantage.


The ability of water to support weight allowing an object to float.


An electrical mechanism that produces an intermittent current and an audible buzzing sound, or series of sounds, when electrical current flows through it.

Glossary - C

Café Wall Illusion

This optical illusion was first observed and described by Doctor Richard Gregory when he noticed the curious effect in the tiles of the wall of a café in Bristol. This optical illusion makes the parallel straight horizontal lines appear to be bent. This illusion consists of alternating light and dark ‘bricks’ that are laid in staggered rows.


A mineral salt that strengthens the bones.

Calcium carbonate

Calcium carbonate (CaCO3) is a common substance found in rock in all parts of the world, and is the main component of shells of marine organisms like snails, pearls, seashells and corals. Saltwater reef tank keepers have to dose or supplement this compound in order for corals to grow. Corals need calcium carbonate to grow.


It is often called the ‘art of fancy lettering’ by means of an ink pen. This style of writing is described as a script and is often used for wedding invitations etc.

Camera obscura

A darkened enclosure in which images of outside objects are projected through a small aperture or lens onto a facing surface. A camera obscura uses the same principles as a regular camera.


A capacitor is an electrical component used to control the flow of charge in a circuit. The name derives from their capacity to store an electric charge. Capacitors consist of two conducting surfaces separated by an insulator; a wire lead is connected to each surface. A capacitor can store electric energy and discharge it at a determined rate.

Capillary action

The flow of liquids through porous media, such as the flow of water through blotting paper.


Made by cooking sugar slowly, used in candy making and sweetening of foods

Carbon dioxide

Carbon dioxide is a colourless, odourless incombustible gas present in the atmosphere. It is formed during the breathing of living organisms, the decomposition and combustion of organic compounds, and in the reaction of acids with carbonates: used in fizzy drinks, fire extinguishers, and as dry ice for refrigeration.


A carcinogenic substance is any substance that produces cancer or stimulates the production of cancerous cells.

Cartesian diver

The Cartesian diver was first explained by René Descartes, a sixteenth-century French mathematician


A substance that initiates or accelerates a chemical reaction without itself being affected

Celestial bodies

Objects that are naturally occurring physical entities or structures, that current science has demonstrated to exist in outer space.


The basic structural and functional unit of all living organisms. Cells can exist as independent units of life (as in monads) or may form colonies or tissues as in higher plants, animals or human beings.

Centre of mass

The point at which the entire mass of a body can be considered to be concentrated. Centre of mass / gravity The point at which the entire mass of a body can be considered to be concentrated.

Centrifugal force

Centrifugal force is the effect that tends to move an object away from the centre of a circle it is rotating about (a consequence of inertia).


A breakfast food prepared from grain

Chemical element

Any of the more than 100 known substances that cannot be separated into simpler substances and that individually or in combination constitute all matter.

Chemical indicator

Any substance used to classify another, often by changing colour.

Chemical reaction

The formation of new substances from one or more reactants, by breaking existing electrical bonds and creating others.


A green-coloured compound or ‘pigment’ in plants that converts radiant energy to chemical energy through the process of photosynthesis.


An analytical chemistry technique for separating and identifying mixtures that are or can be coloured, especially pigments.

Climacteric fruit

The climacteric is a stage of fruit ripening associated with ethylene production and cell respiration rise. Apples, bananas, melons, apricots, tomatoes (among others) are climacteric fruit. Citrus, grapes, strawberries are non-climacteric (they ripen without ethylene and respiration bursts).

Cobalt chloride

A chemical substance often used to predict the presence of water molecules within the air or other substance.


The silky protective case spun by the larvae of some insects and moths in which they metamorphose.


Cohesion is a physical property of a substance, caused by the intermolecular attraction between like-molecules within a body or substance that acts to unite them.

Colour spectrum

The distribution of colours produced when light is dispersed by a prism. The order is displayed in the following order: Red, Orange, Yellow, Green, Blue and Violet.


The opposite of ‘evaporate’. The transition from a gaseous state into a liquid state.


Condensation is the process by which matter transitions from a gas (or vapour) phase into a liquid phase. Dew forming on grass in the morning is a common example of condensation.


The movement of heat through a material as kinetic energy is transferred from molecule to molecule. The handle of an iron pan on the stove gets hot due to heat conduction.


A material that has enough free electrons to allow an electrical current to flow when a potential difference is applied. Conductors are usually metallic in nature, but not always, such as graphite for example.


The transfer of heat through a fluid (liquid or gas) caused by molecular motion. In the atmosphere, convection usually refers to the vertical movement of air masses. An example of convection is the rising of warm surface air and the sinking of cold air from upper levels of the atmosphere.

Convex / Concave

Curving or bulging outward or inward.


Creep is the tendency of a solid material such as soil, to slowly move or deform permanently under the influence of certain forces.

Glossary - D


Dryness resulting from the removal of water.


The amount of matter contained by a given volume. The symbol of density is ρ (the Greek letter rho)


A substance that promotes drying.


A detergent is a material intended to assist cleaning. The term is sometimes used to differentiate between soap and other surface-active chemical cleaning agents widely used in industry and laundering.

Dew point

The temperature at which the water vapour in the air becomes saturated and condensation begins. Dewpoint is expressed as a temperature in degrees Fahrenheit or Celsius.


Dextrin is obtained by hydrolysis of starch. It is a tasteless, odourless gummy substance that is often used as a thickening agent, in adhesives and in dietary supplements.


The process by which a substance moves from an area of high concentration, through a barrier or membrane, to an area of lower concentration.


A unit of measurement of the refractive power of a lens, which is equal to the reciprocal of the focal length measured in meters.


Displacement occurs when an object is immersed in a fluid, pushing it out of the way and taking its place.


Solid matter reduced to a liquid form that has been disintegrated in a solvent.


Deoxyribonucleic acid is a long linear polymer found in the nucleus of a cell and formed from nucleotides and shaped like a double helix. DNA is associated with the transmission of genetic information or all living organisms and some viruses.

Dominant eye

Also known as Ocular dominance is the tendency to prefer visual input from one eye to the other. It is somewhat similar to being right or left handed. The side of the dominant eye and the dominant hand do not always match.


The downward pressure created by the aerodynamic characteristics of a car that allows it to travel faster through a corner by increasing the pressure between the contact area of the tire and the road surface, thus creating more grip.


A usually soluble substance for staining or colouring e.g. fabrics or hair.

Glossary - E


The repetition of a sound resulting from reflection of the sound waves.


Determining the location of something by measuring the time it takes for an echo to return from it.


Determining the location of something by measuring the time it takes for an echo to return from it.


An eclipse is an astronomical event that occurs when one celestial object moves into the shadow of another.


Circulating movement of electrical current within an electrical conductor caused by the intersection of the conductor with a moving magnetic field.

Elastic energy

Potential energy that is stored when a body is deformed as in a coiled spring or elastic band


Any polymer having the elastic properties of rubber.

Electric generator

A device that converts mechanical or kinetic energy to electrical energy. The reverse conversion of electrical energy into mechanical energy is done by a motor; motors and generators have many similarities.

Electric meter

A device that measures the amount of electrical energy consumed by a residence, business, or an electrically powered device.

Electrical current

Electrical current is the flow of charged electrons through a circuit. Electrical current, which is electrons flowing in a wire, can be explained as cars driving along a road, where the road is the wire and the cars are the electrons. The current would be the number of cars passing a given point.


The process by which we generate hydrogen and oxygen from water is called electrolysis.


An electrolyte is any liquid that is able to conduct electricity. Salt water makes an excellent conductor.


An electromagnet is a type of magnet whose magnetic field is produced by the flow of electric current. The magnetic field disappears when the current ceases.


Tiny particles with a negative charge that are capable of creating an electrical current.


The deposition of a metal coating onto an object by putting a negative charge on it and putting it into a solution which contains a metal salt. The metal salt contains positively charged metal ions which are attracted to the negatively charged object and are “reduced” to metallic form upon it.


A simple device that detects the presence of an electric charge by the mutual repulsion of metal foils.


Elodea is a type of aquatic plant often called the waterweeds. Elodea is native to North America and is also widely used as aquarium vegetation.


A minute rudimentary plant contained within a seed.


A chemical that can bind two incompatible items, such as oil and water.

Endothermic reaction

A chemical reaction accompanied by the absorption of heat.


The amount of order or disorder present in a thermodynamic system. Entropy measures how ordered the molecules of a substance are arranged and hence determines whether a material expands or contracts when heated.


Complex proteins produced by cells that facilitates or speeds up certain bio-chemical reactions in the body.

Equilateral triangle

In an equilateral triangle all sides have the same length and the same angles each measuring 60 degrees


Ethylene is an organic gas compound with the formula C2H4. This gas is produced by fruits and vegetables that is rotting and accelerates the ripening and aging process of nearby fruits.


A process by which an excess of plant nutrients, for example nitrogen and phosphorous, reduces the oxygen dissolved within a body of water, producing an environment that does not readily support aquatic life.


The opposite of ‘condensate’. The transition from a liquid state into a gaseous state.


The process of a liquid converting to the gaseous state. Evaporation is a type of vaporization of a liquid, which occurs only on the surface of a liquid.

Exothermic reaction

A chemical reaction in which heat is given off during the formation of new chemical compounds.

Glossary - F


A soft greasy substance occurring in organic tissue and consisting of a mixture of lipids.


A magnetic material containing powdered iron oxide (Fe2O3) which usually has magnetic properties. Ferrous Of or relating to or containing iron. Metals that contain iron as the major alloying element.


A thin wire in a light bulb that is heated white hot by the passage of an electric current. Tungsten is often used.


An impression of the underside of the end of a finger or thumb. It is used for identification because the arrangement of ridges in any fingerprint is thought to be unique and permanent with each person.

Fire extinguisher

Any of various portable steel container devices for spraying and extinguishing a fire with Carbon dioxide or other chemicals.


To be afloat either on or below a liquid surface and not sink to the bottom of the liquid.


A fluid is a substance that continually deforms or ‘flows’. All gases and most liquids are considered to be fluids. The main characteristic of a fluid is that they are capable of flowing and easily changing shape.

Freezing point

The temperature at which a liquid changes state and forms a solid.


The interaction between surfaces: a measure of the resistance felt when sliding one body over another.


The pivot about which a lever turns


An organism of the kingdom ‘Fungi’ lacking chlorophyll and feeding on organic matter.


Also called a ‘fusible link’ is a type of over current protection device. It consists of a metal wire or strip that melts when too much current flows, which interrupts the circuit in which it is connected.

Glossary - G


Galileo Galilei was an Italian astronomer and mathematician who was the first to use a telescope to study the stars; demonstrated that different weights descend at the same rate; perfected the refracting telescope that enabled him to make many discoveries (1564-1642).


A type of ammeter or instrument for detecting or comparing or measuring small electric currents.


A toothed wheel that engages another toothed mechanism in order to change the speed or direction of transmitted motion.

Genetically engineered plants

The alteration of the genome of plants grown for food in order to produce crops with specific advantages.


The process whereby seeds or spores sprout and begin to grow

Golden section

A mathematical or geometrical proportion where the ratio between a small section and a larger section is equal to the ratio between the larger section and both sections put together.


A method of plant breeding widely used in agriculture and horticulture, where the tissues of one plant are encouraged to fuse with those of another.


The force of attraction between all masses in the universe, especially the attraction of the earth’s mass for bodies near its surface. The farther a body from the earth’s surface, the less the gravitational force acting on it.


The process of connecting equipment to a common ground or ‘earth’. This is done as a safety mechanism in order to avoid the unsafe energizing of equipment.

Gyroscopic effect

Having the effect of a gyroscope – a rotating mechanism mounted so that its axis can turn freely in one or more directions. A spinning gyroscope tends to resist change in the direction of its axis.

Glossary - H


A form of energy that is transferred by a difference in temperature.


Helium is the chemical element with atomic number 2 and an atomic weight of 4.0026, which is represented by the symbol He. Helium is a colourless, odourless and tasteless gas. It also makes up a small amount of the air we breathe. It originates from the Greek word ‘helios’ meaning the sun. Helium is commonly used as a cooling agent in superconductors, cryogenics, inflating balloons as well as inflating airships.

Hering Illusion

This is an optical illusion named by Ewald Hering. The vertical or horizontal lines are all straight, but look as if they were bent. The distortion is produced by a lined pattern on the background that simulates a perspective design and creates a false impression of depth.

Hermann Grid Illusion

This is an optical illusion named by ‘Ludimar Hermann’ in the 1800’s. The illusion is characterised by blobs perceived at the intersections of a light-coloured grid between black squares.


A chemical substance produced in a living organism which controls the rate of biochemical processes.


The science of caring for gardens or gardening; small scale agriculture.

Hot-air balloon

Balloon for travel through the air in a basket suspended below a large bag or ‘envelope’ of heated air.


The relative humidity is a measure of the amount of water vapour in the air (at a specific temperature) compared to the maximum amount of water vapour air could hold at that temperature, and is given as a percentage value.

Hydroelectric power

Hydroelectric power is electricity generated by hydropower, i.e., the production of electrical power through the use of the gravitational force of falling or flowing water.

Hydrogen peroxide

An almost colourless, slightly pale blue liquid. H2O2 is soluble in water. Hydrogen peroxide is used as a mild antiseptic and is often found in bleaching agents, especially for bleaching hair.


A technique of growing plants (without soil) in water containing dissolved nutrients.


Measuring instrument for measuring the relative humidity of the atmosphere.


Small threads that are part of a fungus. These thin strands stretch out to gather food and nutrients to allow the fungus to grow.

Glossary - I


Water frozen in the solid state.

Igneous rocks

Rocks that is produced under conditions involving intense heat.


The chemical property where two or more liquids or phases do not readily mix or dissolve in one another, such as oil and water.

Immiscible liquids

Immiscibility is two or more liquids that are not mutually soluble or un-mixable, whereas miscibility is the property of liquids to mix in all proportions, forming a homogeneous solution.

In Parallel

Connected at the same time. Electrical components connected side by side, instead of in series.

In series

Electrical components connected in a chain, instead of in parallel.


A measuring instrument for measuring the angle of magnetic dip. Airplane pilots make use of this device to show the angle that an aircraft makes with the horizon.


Any substance used to classify another, often by changing colour.


An electrical phenomenon whereby an electrical current is generated in a closed circuit, by a stroking a magnet along a conductor.


The tendency of a body to maintain its state of rest or uniform motion unless acted upon by an external force.

Infra-red rays

Invisible radiation in the part of the electromagnetic spectrum characterized by wavelengths just longer than those of ordinary visible red light and shorter than those of microwaves or radio waves.


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

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.

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.


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.


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.


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

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’.

Glossary - J

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.

Glossary - K


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


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


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’.

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.

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.

Knee-jerk reaction

The involuntary contraction of the leg when the knee is tapped with a doctor’s mallet.

Glossary - L


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


A type of a semi-conductor or ‘solid state’ light source. LED’s can produce a very bright light for a small amount of power. LED’s are now used in many applications, for example car brake lights and traffic lights, although white coloured LEDs are still a relatively new technology.

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!


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.


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.


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


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.

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.

Logic gate

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


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

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.


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

Glossary - M


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.

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.

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.


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.


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.

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.


A white crystalline sugar formed during the digestion of starches.


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.


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


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.


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


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.


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.


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.

Metamorphic rock

Rocks formed from other rocks under pressure and extreme heat.

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.

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.


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


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


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


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


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

Morse Code

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

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.


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


The branch of living sciences concerned with the study of fungi.

Glossary - N


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.


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

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.

Glossary - O

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.


Any of a group of fats that is a liquid at room temperature that are obtained from plants.

Optic nerve

The optic nerve transmits visual information from the retina to the brain.

Optical illusion

An optical phenomenon that results in a false or deceptive visual impression.


A specialist in fitting eyeglasses and making lenses to correct vision.


A tuned electronic circuit used to generate a continuous output repetitive variation, typically in time.


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.


Osmosis is the diffusion of a liquid through a cell wall or membrane. Osmosis is the means by which water and nutrients move.


The addition of oxygen to a compound accompanied with a loss of electrons


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.

Glossary - P


A hypothetical continent including all the landmass of the earth prior to the Triassic period when it split into Laurasia and Gondwanaland.

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.


A substance made from paper pulp that can be moulded when wet and painted when dry.

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!

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.


A base, a support or a foundation.


A weight suspended from a pivot so it can swing freely.


A pleasant smell, scent or odoriferous particles emitted from a sweet-smelling substance.


A perimeter is a path that surrounds an area or an object.

Periodic table

A tabular arrangement of the chemical elements according to atomic number as based on the periodic law.


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.


A measure of the ability of a porous material such as the walls or membranes of cells to transmit fluids.

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.


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.


The process that enables plants and some bacteria to capture the sun’s energy and turn it into food and oxygen.


The tendency of plans to move or grow towards light.


A substance whose presence in plant or animal tissues produces a characteristic colour.


The property of sound that varies with variation in the frequency of vibration.


The plastron is the nearly flat part of the shell structure of a turtle or tortoise, what one would call the belly


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.


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.


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’.


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

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.

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.

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)


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.


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


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.


A special type of ratio expressing a relationship between the part and the whole.


The ability of living organisms to sense the position and location and orientation and movement of the body and its parts.


A force causing movement.


Any of the ‘amino acids’ present in all living matter that are an essential food item.


An instrument for measuring or drawing angles on paper, usually a flat semicircular transparent plastic sheet graduated in degrees

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


The rhythmic contraction and expansion of the arteries with each beat of the heart.

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.

Glossary - Q

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.

Glossary - R


The act or process of radiating; the radiation of heat and light from a fire.


An electronic receiver that detects and demodulates and amplifies transmitted signals.

Rain gauge

An instrument meteorologists use to measure the amount of rainfall.


An arc of coloured light in the sky caused by refraction of the sun’s rays by rain.

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.


The fraction of radiant light that is reflected from a surface.


A reflex action, also known as a reflex, is an involuntary and nearly instantaneous movement in response to a stimulus.

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.


The change in direction of a propagating wave (light or sound) when passing from one medium to another

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.


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.


A material’s opposition to the flow of electric current. Resistance is measured in ‘ohms’.


Sympathetic resonance is a harmonic phenomenon wherein a formerly passive string or vibratory body responds to external vibrations to which it has a harmonic likeness.


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.


A delicate, multilayered, light-sensitive membrane lining the inner eyeball and connected by the optic nerve to the brain.


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.

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.


A rocket is a vehicle or object which obtains thrust by ejecting a jet of fast moving fluid exhaust from a rocket engine.


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.


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).


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.

Glossary - S


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.

Salivary gland

Any of three pairs of glands in the mouth and digestive system that secrete saliva for food digestion.

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.


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.


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.


A device that is used to accurately record the motion of the ground during an earthquake.


It allows certain things to pass through while blocking others.

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.

Sheet erosion

Relatively even erosion of a layer of soil without channel formation and generally takes place on sloping land.

Short circuit

An unintentional contact between two points in an electric circuit that have a potential difference.

Sidereal day

The exact time for one complete rotation of the earth relative to a particular star. A sidereal day is about 4 minutes shorter than a mean solar day. Astronomers use sidereal time as a way to keep track of the direction in which their telescopes need to be pointed to view any given star in the night sky. A sidereal day is about 1436.07 minutes.


A tube running from the liquid in a container to a lower level outside the container so that atmospheric pressure forces the liquid through the tube.


A hot vapour containing fine particles of carbon being produced by combustion

Snellen chart

A chart with letters and numbers in lines of decreasing size; used to test visual acuity


Snow is a type of ‘rain’ within the earth’s atmosphere in the form of ‘crystal-like’ ice water, consisting of many snowflakes that fall from clouds.

Soap bubble

A soap bubble is a very thin film of soapy water that forms a sphere with a sparkling surface.

Sodium thiosulfate

Also called ‘hypo’ by photographers, is used to stop development of exposed film and is the last stop for a print before it is rinsed. Thiosulfate converts undeveloped silver bromide grains in the film into water-soluble silver thiosulfate complexes that can be removed when the film is washed.

Soil-burrowing insects

Insects or bugs that live in soil and come out at night when it is dark to consume plants.


Relating to, or derived from the sun or utilizing the energies of the sun.

Solar energy

Energy from the sun that is converted into thermal or electrical energy.


Ships and Submarines often use Sonar to communicate and find their way. Sonar stands for: Sound Navigation & Ranging.

SOS Signal

SOS (Save Our Souls) is the best known international distress signal. Everyone should be familiar with SOS. The SOS signal can be transmitted by any method, visual or audio. The code for SOS is 3 short, 3 long and 3 short signals. Pause. Repeat the signal.

Sound conductor

A material helping to pass on sound waves.

Sound resonance

Soundwaves hitting and bouncing back on the walls of a container in which it travels. The soundwaves are reinforced or enriched by the added sound vibrations.


The portion of the electromagnetic spectrum that is visible to the human eye. Electromagnetic radiation in this range of wavelengths is called visible light or simply light. A typical human eye will respond to wavelengths from about 390 to 750 nm.

Speed of light

The speed at which light travels in a vacuum; the constancy and universality of the speed of light is recognized by defining it to be exactly 299,792,458 meters per second. Einstein’s ‘Theory of Relativity’ implies that nothing can go faster than the speed of light and only objects without mass can travel at this speed.


A sphere is a perfectly round geometrical object in three-dimensional space, such as the shape of a ball.


A spore is a reproductive structure that is adapted for spreading and surviving for extended periods of time in unfavourable conditions similar to a plant seed.


Starch is a carbohydrate consisting of a large number of glucose units joined together. Food rich in natural starch is potatoes, rice and bread

Static electricity

Static electricity refers to the build up of electric charge on the surface of objects.


The art and science of writing hidden messages in such a way that no one, apart from the sender and intended recipient can see or read it.

Stereoscopic vision

The single perception of a slightly different image from each eye, resulting in depth perception.


A stethoscope is a medical device that doctors use for listening to sounds inside the body like breathing or a heartbeat.


Tiny pores on the underside of plant leaves. Carbon dioxide, oxygen and water enter and leave the plant through these tiny pores.


A vessel that is capable of operating submerged under water or below the sea. Also called a ‘sub’ for short.


Animal fat mixture. Woodpeckers are attracted to suet hung in bags from trees.


A supercontinent is a landmass comprising more than one continental core, or craton.


A solution that contains more than the maximum amount of solvent that can normally be dissolved in a given amount of solvent at normal ambient temperature.

Surface tension

A property of liquids in which the exposed surface tends to contract to the smallest possible area, as in the formation of a meniscus. It is caused by unequal molecular cohesive forces near the surface.


Involving or exhibiting symmetry; proportional in parts; having its parts in due proportion as to dimensions; as a symmetrical body or building

Sympathetic resonance

Sympathetic resonance is a harmonic phenomenon wherein a formerly passive string or vibratory body responds to external vibrations to which it has a harmonic likeness.

Glossary - T

Taste buds

Taste buds are receptors for taste. They are located around the upper surface of the tongue, soft palate, and throat.


Temperature is the measure of the average kinetic energy of the particles in a substance, which is related to how hot or cold that substance is.

Terminal velocity

An object is moving at its terminal velocity if its speed is constant due to the restraining force exerted by the air, water or other fluid through which it is moving.

Theory of Relativity

Einstein’s ‘Theory of Relativity’ is seen as one of the most important scientific advances of modern time. Einstein recognized that the speed of light in a vacuum is constant, and an absolute physical boundary for objects in motion. For objects travelling near light speed the theory of relativity states that: objects will move slower and shorten in length from a point of view on Earth. Einstein derived the famous equation, E = mc2, which means that Energy is equal to Mass times the speed of light squared. In simpler terms, it states that there is equivalence between mass and energy.

Thermal insulator

A method or material used to help prevent or reduce the flow of heat.


Thermodynamics is the study of heat. In science, thermodynamics is the study of energy conversion between heat and mechanical work.


We think of time as the ways in which we measure the passing of time, such as a clock or watch, or perhaps a measured interval of time such as an hour or minute.


A destructive windstorm occurring over land, characterized by a funnel-shaped cloud extending toward the ground.


Torque, also called ‘moment’ or ‘moment of force’, is the tendency of a force to rotate an object about an axis, fulcrum, or pivot. Just as a force is a push or a pull, a torque can be thought of as a twist.


The period during a solar eclipse when the Sun is completely blocked by the Moon.


A transmission, also called a ‘gearbox’, is a set of gears that provides speed and torque conversions from a rotating power source to another device using gear ratios.


Transpiration is a process similar to evaporation. It is the loss of water from parts of plants, especially leaves, but also stems, flowers and roots. Leaf surfaces are dotted with openings called stomata, and in most plants they are more numerous on the undersides of the foliage.


The upper arm muscles used for extending the elbow.

True North

True north is the direction along the earth’s surface towards the geographic North Pole.


he unstable flow of a liquid or gas.

Glossary - U

Umbra / Penumbra

The umbra, penumbra and antumbra are the names given to three distinct parts of a shadow, created by any light source. The umbra is the area of total darkness in a shadow caused by an eclipse, while the penumbra is a fringe region of partial shadow around an umbra.

Glossary - V

Variable resistor or ‘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.


The arrangement of veins in a leaf.


The resistance of a liquid to shear forces and hence its ability to flow. For example: Water or alcohol has a low viscosity while oil or honey has a high viscosity.

Vitamin C

Vitamin C, also known as ‘ascorbic acid’, is a water-soluble nutrient essential for life, synthesized by most animals and plants, but not humans, although used in our bodies for many purposes. It is plentiful in citreous fruits and many vegetables. A vitamin C deficiency causes a disease called scurvy.

Vitamin E

A fat-soluble vitamin that is essential for normal reproduction; an important antioxidant that neutralizes free radicals in the bodies of plants, animals and humans.


A rupture in the earth’s or another planet’s crust through which molten lava and gases erupt.


The volt (symbol: V) is the SI derived unit of electromotive force, commonly called “voltage”. A unit of potential equal to the potential difference between two points on a conductor, carrying a current of 1 ampere when the power dissipated between the two points is 1 watt; equivalent to the potential difference across a resistance of 1 ohm when 1 ampere of current flows through it.

Von Frey

Max von Frey was a German physiologist, best known for his investigations into the sensations of pain and touch. Born in 1852, he is known to have established that the skin has separate spots for cold, warmth, touch and pain. Von Frey used a set of hairs, carefully graded from ‘soft’ to ‘stiff’ in experiments investigating physical senses which became known as ‘Von Frey’s hairs’ or a ‘Von Frey device’.


A vortex is the spinning flow of any fluid. The motion of the fluid swirling rapidly around a centre is called a vortex. A powerful circular current of water is referred to as a whirlpool.

Glossary - W

Water pressure

The force exerted by water that has been compressed.

Water turbine

A water turbine is similar to a waterwheel and is a device that uses falling or flowing water to create energy. There are a set of paddles or rotors mounted around the wheel. The force of the water moves the paddles, causing the wheel to turn. The wheel then transmits power to a shaft.

Water vapour

Water in its gaseous state, produced from liquid water by evaporation. Its presence in the atmosphere contributes to humidity.


The watt is a derived unit of power in the International System of Units (SI), named after the 18th-century Scottish engineer James Watt. One watt is the amount of energy used in one second by one ampere current under a voltage potential of one volt.

Weather forecast

A prediction of future weather, often for a specific locality, in a newspaper or on the radio or television.

White light

Light, having a mixture of frequencies, being perceived as having no specific colour, such as sunlight or a white-coloured light or lamp.

Wind vane

A mechanical device attached to an elevated structure. It rotates freely to show the direction of the wind.


A windmill is a machine which converts the energy of wind to rotational motion by means of adjustable vanes or blades.


Work is defined as the result of applying a force to an object in order to move it a certain distance.

Worker ants

All worker ants are females and live about 1-4 years. They are the smallest, but they do the most work. They care for the queen and her eggs. Worker ants build and repair the nest, search for food and fight off enemies.

Glossary - X


A musical instrument made of wooden slats graduated so as to make the sounds of the scale when struck with a small drumstick-like hammer.

Glossary - Y

No terms defined.

Glossary - Z

No terms defined.