This model provides an analogue form visual representation of molecular movement in gases. A piston, in a wide Perspex tube, is vibrated by a low-voltage electric motor contained in a box supporting the tube. Tiny metal spheres, simulating gas molecules, are propelled upwards in a tube by the piston's vibrations. The movements of the spheres are seen to be random both in direction and extent. The motor is provided with a speed control. Higher speeds give more extensive movements of the spheres. The electric motor requires a 6V DC power supply capable of providing a current of 2.5A. For demonstrations to other than small groups, illumination from the side and a black background are recommended.
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