Theme D- Les ombres et la lumiere

Colour - a property of an object produced by the wavelength of light that the object reflects

Concave Lens - curved in like the inner surface of a sphere. Concave lenses tend to spead light out.

Convex Lens - curved out like the back of a spoon. Convex lenses concentrate light by bending the rays to a common point once they pass through the lens.

Dispersion - to spread or scatter. The separating out of different wavelengths of white light into a spectrum of colours as it passes through a prism or drop of water or similar transparent object.

Emit - to give off something as in the sun giving off light.

Kaleidoscope - a tube through which can be seen symmetrical patterns caused by reflections from mirrors.

Light - a form of energy that is emitted by the sun or by a chemical reaction to which the eye is sensitive.

Light meter - an instrument that measures the intensity of light in a particular area.

Luminescent - to glow or to give off light at low temperatures, as in fireflies.

Magnify - to make small things look bigger by looking at them through one or more convex lenses.

Opaque - a material that does not let light pass through. Wood, some plastic and metal objects are opaque.

Prism - a three-sided length of glass. Light passing through it is refracted separating the colour of white light into a spectrum of colours.

Rainbow - nature's display of the spectrum of colours produced by the dispersion of colours as light passes through droplets of water falling through the sky during a rainstorm. Droplets producing specific colours lie in arcs of a circle across the sky which is why the rainbow takes the shape of an arc.

Reflect - to bounce off a surface, as in light bouncing off a mirror.

Refraction - the bending of a light ray as it passes from one medium to another.

Shadow - a dark image or figure cast on the ground or some surface by an object blocking incoming light.

Translucent - a material that allows some light to pass through but scatters the light in the process so that images are not clear (i.e. frosted glass)

Transparent - a material that lets light pass through it so that objects can be seen clearly on the other side

Visible spectrum - a band of colours that make up visible light; each colour is generated by a different wavelength of light - the longest being red and the shortest being violet

White light - light that contains ALL the wavelengths of colour in the visible spectrum from red to violet