Desiccators with knob

A "bell in vacuum" apparatus is a scientific setup used to demonstrate the effects of reduced air pressure (vacuum) on sound transmission. It typically consists of a bell or sound-producing object enclosed within a sealed chamber from which air has been removed, creating a low-pressure environment. This apparatus is designed to illustrate how sound travels differently in a vacuum compared to in normal atmospheric conditions, highlighting the role of air molecules in sound propagation.

The Bernoulli tube apparatus, also known as a Venturi tube apparatus, is a scientific device used to demonstrate the principles of fluid dynamics, particularly the Bernoulli's principle. It consists of a specially shaped tube with a constricted region, often referred to as a Venturi section. When fluid (liquid or gas) flows through the tube, the constricted section leads to changes in pressure and velocity according to Bernoulli's principle, which states that as the velocity of a fluid increases, its pressure decreases and vice versa. This apparatus is commonly used in educational settings to visually illustrate how the flow of a fluid can affect its pressure, helping to explain various phenomena like lift in aircraft wings, fluid flow through pipes, and more.