How does a scanner work?

Scanners are used to create a soft copy of available photos and documents.
When we open the scanner we can see a glass plate. We have to place the document that we need to scan over the glass plate. During the scanning process, a scanning unit moves across the document to be scanned at a speed designated by the
logic board instruction. The scanning unit emits light. The light strikes the document, reflects, and is then reflected by a series of mirrors to the scanner lens. The light passes through the scanner lens and falls over the light sensors. The amount of light reflected from the document is measure and converted into corresponding electrical signal and transmitted to the computer. The electrical signal gives the exact image of the document being scanned and it can be stored in the memory.