# The Ultimate Photocopier Quiz

By: Staff

4 Min Quiz

Image: refer to hsw

The photocopier has evolved from being a luxury to a necessity in any modern office. Many people take the performance of a photocopier for granted. Do you have any idea how these amazing machines produce exact copies of a document?

# What is the one basic physical principle that makes a photocopier work?

Like charges oppose.

# What is a good way to see a simple version of the "opposites attract" principle in operation?

Toner cartridges do not generally have a charge, but you can generate a static charge on a balloon by rubbing it on a sweater and stick it to a wall. You can do the same thing with a plastic comb by combing long hair briskly and then put it near to bits of paper and the paper will jump to the comb.

# How does an image get from the paper onto the copier drum?

The drum is selectively charged by static electricity to match only the black spots on an original. Toner is attracted to the drum only where there is a static charge relating to the black on the original.

# How is selective static charging accomplished on a photocopier drum?

The selective static charging of a photocopier drum is achieved by using light focused through lenses and mirrors.

# What electrical charge does toner carry before being exposed to a charged drum?

Toner carries a negative charge before it is exposed to the drum, where the positively charged areas of the drum attract and hold toner.

# What happens with your original document after you place it on the glass and press the start button?

The document is subjected to focused intense incandescent light moving from one end of the page to the other. Light is reflected from white areas of the paper to strike the rotating drum below.

# What is the electrical state of a drum before light is reflected onto it from your original?

The entire surface of the drum is charged with a positive charge. The light reflected by white areas of your original removes positive charge from the drum in the spots where light hits.

# How does light manage to remove the positive charge from areas on the drum?

Wherever a photon of light hits the photoconductive drum, emitted electrons neutralize the positive charges. The dark areas on the original do not reflect any light leaving corresponding positive charges on the drum.

# What is the toner that is used in a photocopier?

Toner is not an ink but rather a fine plastic-based powder that is negatively charged. In the old days, toner was made with carbon, which has been replaced by several different polymers to improve copy quality.

# What is the coating of photoconductive material on the drum usually made from?

Many photocopier drums have a coating of a semiconductor called selenium on them to form a photoconductive coating. Silicon and germanium are also used for this purpose, but less frequently.

# How does toner that is held on the drum make its way to a sheet of blank paper to form a copy?

The paper is given a positive charge before it passes the drum and this positive charge pulls the toner away from the drum and onto the paper.

# How does the toner manage to stay on the paper once the paper looses its positive charge?

The paper containing the image is heated and pressed in order to fuse the toner image to the paper. This is why toner is made from pigmented plastic beads, which melt, making a bond with the paper.

# What components inside a photocopier charge the drum and paper with a positive charge?

The corona wires inside the photocopier are electrified with a high voltage, which they subsequently transfer as a positive charge, to a drum or a blank piece of paper in the form of static electricity.

# What function does the lens have in a photocopier?

The lens serves to focus an image onto the drum below it and allow reduction or magnification of an image. Unfortunately, there is no lens to improve on the clarity of any original document.