External Hardware Devices PMT Paper 2

• What are input and output devices used for in computers?

  To allow data input and output
• How do barcode readers identify products in supermarkets?

  By reading barcodes printed on items
• What do barcodes consist of?

  Light and dark portions
• What are the two main types of barcodes?

  1D and 2D barcodes
• How do 2D barcodes differ from 1D barcodes?


  2D barcodes hold more information
• What components make up a barcode reader?

  Laser, lens, photodiodes, and mirror
• What happens to light reflected by a barcode?

  It passes through the lens to photodiodes
• How does a photodiode function in a barcode reader?

  It converts light into electrical charge
• What do light and dark portions of a barcode represent?

  Binary 1s and 0s
• What methods can barcodes use for error detection?

  Parity bits and check digits

  
• What happens if a barcode fails to scan correctly?

  The reader continues scanning until successful
• How fast can barcode readers scan?

  Thousands of times per second
• What is the main function of a digital camera?

  To capture images digitally
• What regulates the path of light in a digital camera?

  The shutter
• What are the two common sensors used in digital cameras?

  CMOS and CCD
• How do sensors in digital cameras work?

  They convert light into electrical charge
• What happens to the charge in sensor cells after a photograph is taken?

  It is measured and converted to digital value
• How do color cameras capture images?

  By using multiple cells for each pixel
• What is a Bayer filter used for in digital cameras?

  To approximate human eye sensitivity
• What is the function of a laser printer?

  To produce images on paper
• What components are found in a laser printer?

  Laser, mirror, drum, toner roller, fusers

  
• How does a laser printer create an image on the drum?

  By discharging areas with a laser
• What attracts toner to the drum in a laser printer?

  Opposite charges between toner and drum
• What colors of toner are used in color printers?

  Cyan, yellow, magenta, and black
• What does RFID stand for?

  Radio frequency identification
• What is the purpose of RFID technology?

  To transfer information wirelessly
• What is inside an RFID tag?

  A chip and a coil of wire
• What happens when an RFID tag is scanned?

  The tag emits its own radio wave
• How do passive RFID tags operate?

  By inducing power from the reader
• What is the primary function of secondary storage devices?

  To store files and applications
• What is a hard disk drive made of?

  Circular platters made from magnetic material
• How does a read/write head function in a hard disk drive?

  It changes the magnetic polarity of the platter
• How is data organized on a hard disk drive?

  In concentric tracks and sectors
• What is the typical capacity range for hard disk drives?

  500GB to 5TB
• Why are hard disk drives unsuitable for portable devices?

  They are susceptible to damage from movement
• What do solid-state drives consist of?

  NAND flash memory cells and a controller
• What is the advantage of NAND flash memory?

  It is non-volatile and retains data without power
• How is data stored on SSDs?

  In pages combined to form blocks

  
• How do SSDs differ from HDDs in data writing?

  SSDs must erase a page before writing
• Why are SSDs suitable for portable devices?

  They have no moving parts and are durable