The Light Guide Demonstrator is used for showing how the phenomenon of total internal reflection may be used to confine light within a guide or fibre thus leading to an appreciation of the principles of optical communications.Comprising an acrylic bar (220mm x 20mm x 20mm) formed into a shallow 'S' shape. Whilst the shape of the bar prevents the direct passage of a light ray if such a ray (from a light box or laser) is introduced into one end it can be seen to be reflected several times from the internal surfaces of the bar to emerge from the other end. The lower surface of the bar is painted white to aid visibility of the path of the light ray.The Light Guide Demonstrator is also available to purchase as a pair with the LED.white by Unilab (B8R00001).