... as it contacts the surface of the belt. It occurs for the same reason that a balloon becomes charged with static electricity when rubbed on clothing. The belt and roller surfaces become statically charged. The belt becomes weakly positive (because the charge is spread widely on the belt) and the roller becomes strongly negative (because the charge on the roller is much more concentrated). Because of this strong concentration of negative charge the roller begins to do two things. Firstly, it repels the electrons near the tips of the lower brush assembly and the brush now has positively charged tips. Secondly, it begins to strip air molecules of their electrons. Air molecules are torn by intense electric attraction/repulsion forces. A mass of shattered and free electrons form. This is called corona discharge. Free electrons and positively charged atoms of air exist between the roller and the brush. The positively charged atoms are attracted to ...

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