Working of a Photocopier

• The drum is shown, it comprises of a coating of selenium. Selenium is a photo conductive material; the property of a photo conductive material is that when light falls upon it, it gets charged. The drum gets charged by high voltage wire. The document to be photocopied is illuminated by light, the white part of the document reflects maximum amount of light, when this light falls on the drum, the negative charged gets diminished by earthing; the written material on the document reflects least amount of light, and corresponding areas of the drum have negative charge. Thus a virtual electrical image is formed on the drum.

• The toner are small particles of ink which are positively charged, they get attached to the negatively charged particles on the selenium.

• The paper which is inserted is attributed a negative charge, which is higher in magnitude as compared to the negative charge on the drum. The toner particles get attached to the paper. The toner is melted and fused in the paper, by a combine action of heat and rolling effect.

• The drum continuously roates during the process of photocopy. Before the next cycle of photocopying begins, the drum is discharged.