The Challenge: Make an underwater flashlight
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Why does the filament
through the filament is essentially just electrons moving along the wire.
The movement of these electrons isn't smooth: as well as moving in one
direction, they are also bouncing around, hitting each other. The nuclei
of the atoms of the wire form a lattice that the electrons have to move
across. The material is described as having a 'resistance' to the electron
flow. The more resistance the metal offers, the more electrons bash each
other and the nuclei and the hotter the material gets.
The heat energy gets
other electrons, still trapped around the metal atoms' nuclei, excited.
The energy pushes the electrons further away from the nuclei of the atoms.
As the electrons fall back, they emit photons of light.
along the filament
Making a light bulb