Consists of a polished acyrlic tube with a notch cut out of one end so that a laser pointer can be shone 'into' the cylinder wall.

Show total internal reflection. When the angle of incidence of light onto certain surfaces is sufficiently oblique, light is entirely reflected rather than refracted and partially reflected.

• Internal Reflection tube
• Laser pointer

Simply place the tube on a table and shine a laser pointer¹⁾ into the notch on the bottom. You should the entire top surface of the cylinder glow green, and the beam should be visible for at least one revolution around the circumference.

Currently some paper has been taped to the inside surface of the tube to improve contrast and make the beam more visible.