TestOut LabSim A+ Certification Practice Exam

Which component in a laser printer applies toner to the drum?

1. Fuser unit

2. Developing roller

3. Duplex unit

4. Toner cartridge

The correct answer is: Developing roller

The developing roller is a crucial component in the laser printing process that applies toner to the drum. When the printer receives a print job, it uses a laser to create an electrostatic image on the photosensitive drum. The developing roller then has toner, which is a fine powder, that is charged in such a way that it adheres to the areas of the drum that have been exposed to the laser light. Once the toner is applied to the drum, the drum rotates, and the toner is transferred to the paper as it moves through the printer. After the toner is transferred, the image is permanently fixed to the paper by the fuser unit, which uses heat and pressure to bond the toner to the paper fibers. Each of the other components plays its specific role in the laser printing process, but they do not perform the direct function of applying toner to the drum. The fuser unit is responsible for fixing the toner onto the paper, the duplex unit is involved in printing on both sides of the paper, and the toner cartridge contains the toner but does not apply it directly. This specific function of the developing roller is critical to ensuring the correct amount of toner is applied for a high-quality print output.