How Does a Hair Dryer Work?
If you don't have the time to let your hair air dry, or you're looking to control the wave and body in your hair, using a hair dryer might be for you. But just how does a dryer work?
The most important component in a hair dryer is an electric fan. Unless the weather is very humid, the water on your hair will evaporate on its own, but it will do so slowly. The fan in a hair dryer blows air into a tube that sends it in a focused jet. This jet of air pulls off droplets of water and increases the rate of evaporation, greatly speeding the rate at which your hair dries.
The Heating Element
The heating element further speeds up the rate at which your hair dries. The heating element is made out of a resistor, such as nichrome wire. A resistor literally resists the flow of electric energy, turning it into heat energy. In a hair drier, the air blows past the resistor, absorbing heat as it passes.
Normally, evaporation is controlled by relative humidity -- the ratio of the amount of water the air holds to the amount it could hold. For example, if the relative humidity is 90%, that means that the air is holding 90% of its maximum volume of water. When air is heated, its relative humidity decreases. It still has the same amount of water, but it can hold more. The lower the relative humidity, the more easily water evaporates. Therefore, hot air will dry your hair faster, since the water in your hair will evaporate more quickly.