Question

List all the internal components of a hair dryer and explain the physics concepts involved.For electricity and magnetism you can discuss Faradays law, Lenz Law, Back emf, Ohms law, flux, induced emf etc. If there  is a mechanical component, such as axle, gear, pulley, bearing etc. discuss how it utilizes the classical mechanics that you have learnt.Does it take the advantage of torques or lever arms?Does it make the device more efficient? Is it the example of Newtons laws?

Answer 1

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Principle

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 parair will dry your hair faster, since the water in your hair will evaporate more quickly.

The two important components of a hair dryer are the electric fan and the heating element.

The heating element is made out of nichrome wire, which is a resistor. A resistor 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. Electric hair dryers work by blowing room temperature air in through the vents.

The air then passes over nichrome wire coils that heat it, making it able to blow the hair dry with hot air. The process of air blowing on the hair speeds up water evaporation. Applying power to the hair dryer allows the motor to start spinning the fan inside, and that is what draws the air in through small air holes on the side of the dryer.

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