A paper. This paper then passes through two

A photo copy machine has components such as a halogen lamp, photo sensitive
drum, toner or the ink drum, and conveyor belt. When you place the document you want to
be copied upside down on the glass and press the start button, an intense beam of light
scans across the document from top to bottom and this light then gets reflected and falls the
photo sensitive drum. This photo sensitive drum is a metal which is electrostatically charged
by a high voltage wire called a corona wire. It is a semiconductor so it has the property to
act as an insulator in dark areas and when light falls on it, it conducts electricity.
When a beam of light was scanned across the document, light will reflect the white
areas, however printed letters being black do not reflect any light. When the reflected light
falls on the photo sensitive drum, the areas of the photo-conductor which was exposed to
light becomes conductive and gets discharged whereas the area of the drum which was not
exposed to light remains negatively charged. When this photo sensitive drum rotates, it
carries an electrical shadow towards the toner. The toner is positively charged, so it sticks
to the electrical shadow which is negatively charged and an inked image of the document is
formed on the drum. Then a blank sheet of paper is feed up from the hopper, as it moves
along, the paper is given a strong electrical charge. The toner image is transferred from the
surface of the drum onto a piece of paper. This paper then passes through two hot rollers.
The heat and pressure from rulers permanently fuses the toner particles on the paper.
On the other hand, a laser printer uses a computer output to program the intensity
of a laser beam onto the selenium-coated drum. At first the selenium’s drum is positively
charged, the laser gets signal from the computer then it hits down at different points and it
becomes negatively charged. In a tonner hopper, it has a powder in it which is like ink foot
paper and this powder is positively charged. When the drum goes near it, the powder is only
attracted to the negative part of the drum and sticks to it, forming reverse words on the
drum. Now the paper is negatively charged. It has a stronger charge than the drum so when
the drum with the powder on it touches the paper, the powder is transferred from the drum
to the paper. The paper now has words on it.