How does a hair dryer work?

A hair dryer is a fan and 3 metres of hot wire in a plastic tube. Inside every hair dryer is a small motor spinning a fan, and a heating element: about 3 metres of thin nichrome wire, coiled and wound on a frame of heat-proof mica.

Read how it works: How does a hair dryer work? · The history of the hair dryer · More boxes on Glassbox

Chapters in this interactive model

1. Inside a hair dryer: A fan, a hot coil of wire and a few clever safety parts, in a plastic tube.
2. Heat from a hot wire: Push current through a stubborn wire and it gets hot: P = V² ÷ R.
3. Hot, fast air dries hair: The heat balance ΔT = P ÷ (ṁ × cp), and why speed matters as much as heat.
4. When the air can’t get in: Block the inlet and the dryer overheats. A bimetal disc and a fuse step in.
5. What heat does to a hair: Hydrogen bonds, keratin coils, and where heat starts to do damage.
6. Water, shocks and the bill: Why a dryer in the bath can kill, how an RCCB saves you, and what a dry costs.