External hardware devices

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

  They allow computers to use data.
• What is the purpose of a barcode reader in supermarkets?

  To identify products being purchased.
• What do barcodes consist of?

  Light and dark portions.
• How do 2D barcodes differ from 1D barcodes?

  2D barcodes can contain more information but require more processing.
• What components make up a barcode reader?

  A laser light source, a lens, photodiodes, and a mirror.
• How does a barcode reader convert light into a digital signal?

  The photodiode turns light into electrical charge, which is processed into a digital signal.
• 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 to scan until it reads the barcode successfully.
• How many times can barcode readers scan per second?

  Thousands of times.
• What is the function of a digital camera's lens?

  To focus light onto a sensor.
• What are the two common sensors used in digital cameras?

  CMOS and CCD.
• How is light converted into a digital image in a digital camera?

  The charge in each cell is measured and converted to a digital value.
• How do color cameras create full-color photographs?

  By building separate images for red, green, and blue light intensities.
• What is a Bayer filter used for in digital cameras?

  To allow different wavelengths of light to pass through for color imaging.
• What is the main function of a laser printer?

  To produce images on paper from digital signals.
• What components are involved in the operation of a laser printer?

  A laser light source, a mirror, a drum, a toner roller, and fusers.

  
• How does a laser printer transfer toner to paper?

  The toner is attracted to the positively charged portions of the drum and then applied to the paper.

  
• What colors of toner are used in color printers?

  Cyan, yellow, magenta, and black (CYMK).
• What does RFID stand for?

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

  To transfer information wirelessly between a tag and a reader.
• What components are found inside an RFID tag?

  A chip with memory and a coil of wire acting as an antenna.

  
• How do passive RFID tags operate?

  They induce power wirelessly from the reader to operate the chip.
• What happens when an RFID tag is scanned?

  The reader emits radio waves that power the tag, which then sends back information.

  
• What is the primary function of secondary storage devices?

  To store files and applications.
• What are the types of secondary storage devices mentioned?

  Hard disk drives (HDDs), solid-state drives (SSDs), and optical disks.
• How does a hard disk drive (HDD) store data?

  Data is written in concentric tracks divided into sectors on magnetic platters.
• What is the typical capacity range for hard disk drives?

  Between 500GB and 5TB.
• Why are hard disk drives unsuitable for portable devices?

  They have many moving parts and are susceptible to damage from movement.
• What are solid-state drives (SSDs) made of?

  NAND flash memory cells and a controller.
• What is a key advantage of SSDs over HDDs?

  SSDs have no moving parts, allowing for higher read and write speeds.
• How is data stored on SSDs?

  Data is stored in pages, which are combined to form blocks.

  
• What is the main function of optical disks?

  To store information that can be read optically by a laser.
• What are the three types of optical disks mentioned?

  CDs, DVDs, and Blu-rays.
• How do pits and lands function on a read-only optical disk?

  Pits are burnt into the disk, affecting how light is reflected back to a photodiode.
• How does a laser read data from an optical disk?

  It reflects light back onto a photodiode unless it hits a pit, which scatters the light.
• What is the difference between recordable and rewritable optical disks?

  Recordable disks use a dye that changes state once, while rewritable disks can change state multiple times.
• What are the key differences between hard disk drives (HDDs), solid-state drives (SSDs), and optical disks?

  • HDDs: High capacity (500GB to 5TB), good read/write speeds (~100MB/s), high latency, bulky, high power consumption.
  • SSDs: Lower capacity (typically under 1TB), very high speeds (~500MB/s), very low latency, lightweight, low power consumption.
  • Optical Disks: Very low capacity (Blu-rays at 25GB), relatively low speeds (~30MB/s), high latency, small and lightweight, high power consumption.
• What is the typical capacity of Blu-ray optical disks?

  25GB.
• What is the read/write speed of a solid-state drive (SSD)?

  Approximately 500MB/s.