Segment V11.1: Lighter Flame

(Related to Textbook Section 11.1 - Ideal Gas Relationships)

For an ideal gas the relationship among the pressure, density, and temperature is given by the ideal gas law. A change in pressure, temperature, or gas constant (type of gas) changes the density.

Density differences can be made visible by use of a Schlieren optical system that uses the fact that the speed of light in a gas is a function of its density. Because butane has a different density than air (different gas constant), unlit butane gas escaping from the lighter is visible as a small plume. When the lighter is lit, air surrounding the flame is less dense (higher temperature) than the room air. A large buoyant plume is produced. (Iowa State University Mech. Engr. Schlieren system courtesy of Professor W. J. Cook)