Scanning Microscopy


Aluminium and copper wires were burnt by electric short circuit and by outside flame. These wires have been studied under scanning electron microscope with a view to distinguish them in fire cases. It was observed that there were extensive grains on the cylindrical surfaces near the ends of copper wires burnt by electric short circuit. The grainy structures were continuously decreasing with distance from the ends and vanished. Aluminium wires had bucklings starting from the ends and decreasing on subsequent portions. These features were found to have a potential advantage to identify the ends specially those which did not have beads but produced by electric short circuit. However, the wires burnt by outside flame showed heterogeneous surface structures including ditches and separations at different places. Their ends were mostly pointed ones. Reddish crystals of cupric oxide and black tripaziums of cuprous oxide were observed in the ditches of copper wire.

The distinctive features of two types of burnt wires revealed by scanning electron microscope can be utilised in fire cases to assess if the wires were burnt by electric short circuit or otherwise.

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