High School Physics

How static electricity is used in Laser Printer?

Laser printers use static electricity to print documents. Let’s see how it is done.

  • Inside the printer, an object called the image drum is given a positive charge.
  • A laser is then shone onto the drum.
  • This creates a negative charge on parts of the drum (see Figure 1).
  • This negative charge is given the shape of whatever is to be printed.
Figure 1: A laser is shone onto a positively charged image drum
  • Powdered ink (toner) inside the printer is given a positive charge.
  • Thus the toner is attracted towards the negatively charged areas of the image drum.
  • Negatively charged paper is then rolled across the image drum.
Figure 2: Paper being rolled across the image drum and attracting the ink.
  • The charge on the paper is stronger than the charge on the image drum.
  • so the powdered ink on the drum sticks to the paper (Figure 2).
  • The paper is then heated, fusing the ink powder to the paper.

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