Physics

Uses of Static Electricity in Photocopier

Nowadays photocopier or photocopy machine is very essential and thus it has become very popular machine. Not only the educational institutions and other offices but also general people use this machine to photocopy any kind of necessary papers and documents. Static energy is also used in this machine. There is a rotating dram inside the dark part of the photocopier. Positive charge is sprayed over the dram. A bright light lights up the page to be photocopied. The white part of the page reflects light but the dark or printed part does not reflect light. The reflected light centers on the dram.

Charges releases from the part of the dram where the reflected light from white paper falls. Only the dark part of the dram is charged positively. Negatively charged ink of carbon powder (toner) is sprayed over the dram. Negatively charged ink particles get stick to the positively charged part of the dram. A piece of white paper is positively charged and is kept pressed with the dram. This paper picks up the pattern of carbon powder on its surface from the dram. Positively charged paper attracts the negatively charged toner.

Then the paper is passed through the heated roller. As a result the ink of the toner gets melted and mixed with the paper and makes a permanent copy.