Explosive sparksYilmaz AlpaslanAward: Top 100
School: ted ronesans college When the tip of the wire coming out of my 9V 3A adapter makes contact with the surface of a grounded aluminum foil, an unusually high current discharges to it due to electrical potential difference between the positive end of the wire and the foil, well exceeding the current limit of the adapter which takes time to activate. However, due to the irregularity of the surface of the foil, this happens way more than once, bypassing the current limit each time, and building up heat caused by electrons in the wire constantly hitting the lattice atoms of the metal while accelerated by the electric field generated by the adapter. In result of this, the aluminum melts almost instantly. The white lines in the picture are trajectories of molten aluminum exploding out of the point of contact with high velocity caught by the camera because of its relatively long exposure. The white-orange color indicates that the temperatures reached are as hot as 4500°C, which is inferred by the fact that the electrons vibrating inside each aluminum atom induce electromagnetic waves, frequencies of which reach the visible spectrum. This is called Planck's law of black-body radiation. Sudden changes in the trajectories of some particles seen in the photo illustrate interaction with the surrounding air, and the color gradient seen from blue to bright orange exemplifies thermal conduction. 
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