Energy and Change Glossary

  • ammeter: device that measures the strength of an electric current

  • ampere: the standard unit for measuring electric current

  • angle of incidence: the angle between the incident ray and the normal line

  • angle of reflection: the angle between the reflected ray and the normal line

  • attract: to pull something closer

  • cell: a source of energy for an electric circuit

  • component: a part of a larger system

  • composition: the parts of a mixture

  • conductor: a substance which easily transmits electricity, heat, sound or light

  • converge: light rays that come together and focus on a point

  • delocalised: not limited to a particular place, free to move

  • discharge: the sudden flow of charged particles between two electrically charged objects

  • dispersion: spreading of something over an area

  • diverge: light rays that spread apart as they move further and further away from a point

  • earth: (or ground) to connect with a conductor to the ground, or the earth

  • earthing: a way to prevent electrical charge from building up on an object, or to neutralise an electric charge, by allowing the excess charge to flow into the Earth

  • electric circuit: a complete path through which electrons can move

  • electric current: the movement of charge in an electric circuit

  • electrodes: a conductor which allows electricity to enter a substance

  • electrolysis: the use of electricity to separate chemicals in a solution

  • electromagnet: a device which becomes a magnet when electric current passes through it

  • electroplating: covering an object with a thin layer of metal using electrolysis

  • electrostatic charge: the electric charge resulting from static electricity caused by an excess or deficiency of electrons on the surface of an object

  • flammable: something is easily set on fire

  • focus: bring together to the same point

  • friction: the resistance that results when two surfaces are rubbed or moved against each other

  • fuse: a safety device designed to melt and break the circuit if an electric current reaches too high a level

  • ignite: to light something

  • incident ray: the ray of light which hits a surface

  • luminous: bright or shining

  • medium: substance through which waves (such as light) can travel

  • neutral: when the number of positive charges (from the protons) is equal to the number of negative charges (from the electrons); the (positive and negative) charges balance each other so that the object is neither positively nor negatively charged

  • normal line: this is an imaginary line which is drawn at 90o to the surface

  • opaque: something that you cannot see through; no light passes through the object

  • optical density: a measure of how well a medium allows light to travel through it

  • optics: the scientific study of sight and the behaviour of light

  • parallel circuit: a circuit that provides more than one pathway for the current to pass through it

  • perpendicular: at right angles

  • propagation: spreading into new areas

  • qualitative: describing something in terms of its properties or characteristics rather than by a number or measurement

  • radiation: the emission of energy as electromagnetic waves

  • rectilinear: straight lines

  • reflect: throw back without absorbing

  • reflected ray: the ray of light which leaves a surface

  • refraction: the change in direction of a wave passing from one medium to another caused by its change in speed

  • repel: to push something away

  • resistance: the opposition to the movement of charge in a conductor

  • resistor: a component in an electrical circuit which slows the movement of charge

  • retina: a layer at the back of the eyeball which is made up of light sensitive cells

  • series: components connected in series provide only one pathway for electrical current; they are connected one after another

  • static electricity: the build-up of a stationary electric charge (either positive or negative) on the surface of an object

  • stimulate: to cause activity

  • switch: a control component in an electrical circuit which opens or closes the circuit

  • translucent: semi-transparent; some light is able to pass through but not enough for details to be seen clearly

  • transmit: to cause light to pass through space or medium

  • transparent: something that you can see through; light passes through the object

  • variable: something that can vary or change

  • visible spectrum: the portion of the wave spectrum that is visible to the human eye