Fire and Light Bulbs
The most ancient of discoveries and the epitome of invention,
fire and light bulbs both provide light by the same process: incandescence.
In fire, from forest fires to Bunsen burners, chemical reactions
release heat, releasing gases and raising materials to high temperatures,
where the gases and materials incandesce. Depending on the reactants,
different temperatures are produced resulting in different colors.
Also, certain chemicals can tint the color of the flame. In a Bunsen
burner, the reactants are primarily methane (CH4) and oxygen (O2).
The products are also simple: water (H20) and carbon dioxide (CO2).
When you look at the flame from a Bunsen burner, you can see different
sections with different colors. These differences are due to variations
in heat (the hottest point is the tip of the inner cone) and also
the chemicals being heated. In forest fires by contrast, the reactants
are organic molecules in the wood. These are fairly complex with
many portions being incombustible, so the product of the fire contains
many impurities and the fire is much cooler. Thus, wood fires tend
towards orange-yellow, or reddish when they die out.
Light bulbs also produce light through incandescence, but they
use electricity to produce the heat. Inside a light bulb, as in
electric coil heaters, electrical current runs through a thin
wire and heats the wire to a high temperature, causing the wire
to incandesce. Brighter (and whiter) light requires higher temperatures,
which in turn require more electricity. You can figure out how
much energy is being used by a light bulb by looking at its watt
rating. A watt is equal to one joule of energy per second, so
a 100 watt light bulb uses 360,000 joules an hour, enough energy
to lift a ten kilogram (22 pound) object 3600 meters (2.3 miles)!
It's all in the phosphors