Bottle and Tube

Gas filled bulb and U-tube manometer

Ball and ring; Plate with hole

Relevant Resource questions :

Concepts demonstrated :

• thermometer
• thermal expansion of a gas
• constant volume gas thermometer

Equipment needed :

• gas thermometer
• beaker
• retort stand
• bunsen burner and matches

• Mount the thermometer on the retort stand.
• Place the bulb in a beaker of water to measure the temperature.
• Heat the water in the beaker using the bunsen burner.

None

Physics involved :

This experiment demonstrates the relationship between P and T (from PV = nRT) by removing the change in volume of the gas.

The air in the bulb expands (or contracts) when heated (or cooled) and moves the mercury level. The new level is proportional to the difference in temperature. more needs to be said on this.

How to use the Demonstration :

• Ask the students how they could measure pressure without changing the volume of the working medium.
• Show them the demonstration and ask them to explain the process.

Things to do or add :

Other Comments :

• This is a classic but awkward and time-consuming demonstration.