4A10.20 Galileo Thermometer

The spheres have different densities and are marked in 4 degree increments. Which float and which sink varies with temperature. Can be used as visual aid in talking about measuring temperature or what determines whether something sinks or floats. You can demonstrate the effect of changing temperature by placing thermometer in container of cold water.

Setup: Off the shelf if used as visual aid. Ask ahead of time if you want to put it in a container of cold water.

Equations: An object floats if it has a density lower than the fluid. The density of the fluid will vary with temperature.

Safety Issues: Broken glass.

4A30.10 Bimetal Strip

Strips of dissimilar metals bonded together bend when heated due to expanding by different amounts.

Setup Requirements: Minimal. Use Bunsen burner or hotplate

Equations: L =L_o( 1 + alpha x delta T)

Safety Issues: Gas explosion, flame, red hot hotplate

4A30.11 Thermostat Model

Demonstrate how older type thermostats work.Heat metal strip on top with match or fire starter until breaks/makes contact. Light bulbs swap being on or off.

Setup Requirements: Minimal. Requires AC power and match or "fire starter"

Equations: None

Safety Issues: AC line voltage present, flames

4A30.12 Expanding Wire

Demonstrate change in length with temperature change. Length of wire increases when heated. Pointer attached to wire moves along scale.

Setup Requirements: Minimal. Use "fire starter" device or small blue torch to heat. 

Equations: L = L_o( 1 + alpha x delta T)

Safety Issues: Flame

4A30.20 Balls and Ring 

Demonstrate effect of heat on size. Does diameter of ring/ball increase or decrease? Pull ball on chain through hole and heat until it is too large to go back through hole. Heat other ring until ball that was too large goes through.

Setup Requirements: Minimal. Requires Bunsen burner or hotplate.

Equations: Change in diameter is proportional to diameter x (change in temperature).

Safety Issues: Flames, gas explosion, red hot hotplate

4A40.30 Brittle Fracture

Cool a flower, clay or fruit in a Dewar of liquid nitrogen and smash it. Brittle fracture is a practical problem that affects ships and nuclear reactors.

Setup Requirements: Two working days advance warning or bring your own LN. Bring things to smash. Apples recommended. Only clay in stock.

Equations: None

Safety Issues: Liquid Nitrogen