9 External Hardware Devices

Question 1

What are the three main secondary storage devices?

Answer 1

Hard disk
Solid state drive
Optical disc (CD)

Question 2

What are laser printers used for?

Answer 2

Printing out word documents

Question 3

Name 5 benefits of laser printers over ink jet.

Answer 3

1. Higher paper and ink capacity
2. Text is sharper
3. Cheaper
4. Faster
5. No wet pages

Question 4

Name 2 disadvantages of laser over inkjet printers?

Answer 4

1. Can only effectively print in two tone. Therefore can only print text and not graphics.
2. Higher initial costs

Question 5

Explain the principles of operation of a laser printer:

Answer 5

1. Drum is coated in positive charge
2. Laser beam that removes positive charge shone at drum
3. Drum is covered by positively charged toner which sticks to areas hit by laser.
4. The drum is rolled on the paper and the toner is transferred

Question 6

Explain the principles of operation of a barcode reader:

Answer 6

1. A mirror directs a laser light across the barcode
2. The light areas of the barcode reflect light back
3. The lens focuses reflected light onto a photodiode
4. The photodiode converts the light into an electrical charge that is processed as a digital signal
5. If there is an error this process repeats (very quick)

Question 7

Name 4 advantages of barcodes

Answer 7

1. Quicker than entering data by hand
2. No errors from faulty inputs
3. Barcode can contain more information than a paragraph could
4. If slightly scratched horizontally will still run as long as a thin strip of the barcode is undamaged

Question 8

Name 3 disadvantages of barcodes

Answer 8

1. Barcode could be damaged vertically making it unreadable
2. Barcode reader may need cleaning
3. Requires relatively expensive hardware

Question 9

Explain the principles of operation of a digital camera:

Answer 9

1. Light enters through a len and is focused on to the CCD
2. The cells convert the different light intensities into different electrical charges
3. An ADC converts each charge into a digital signal
4. A colour filter is applied to create data values for red blue and green components
5. Each cell represents one pixel

Question 10

Describe the two methods for taking colour photos:

Answer 10

1. Light is split into three paths red, green and blue. Each colours intensity is measured by its own sensor.
2. A mosaic of red green and blue filters is placed over censors removing some colours from each pixel. The amount of the lost colour in each pixel is then calculated based on the amount of it present in nearby pixels.

Question 11

What is the disadvantage and advantage of splitting light in a digital camera?

Answer 11

Disad: cameras need three sets of censors so are bulkier
Adva: creates higher quality images

Question 12

State 4 benefits of digital cameras:

Answer 12

1. Can store a lot of photos easily
2. Photos can instantly be viewed on screen once viewed and copies can easily be made
3. Photos can be manipulated easily
4. No need to develop photos which is arduous

Question 13

Describe the principle of operation of an RFID tag.

Answer 13

1. Reader emits radio waves that induces a small current in the RFID ta
2. This triggers the tag to emit a radio wave containing the data in the tag
3. The reader picks up this signal and decides the information

Question 14

Name 3 advantages of RFID tags.

Answer 14

1. Can be overwritten unlike barcodes
2. Multiple tags ca be read simultaneously
3. Reduces human effort and error

Question 15

Name 4 disadvantages of RFID tags.

Answer 15

1. RFID tags have low range
2. Initial cost to set up RFID system is high
3. EM interference can disrupt transmission of data
4. Credit cards can be scanned by hackers without your knowledge

Question 16

What is the difference between a passive and active RFID tags?

Answer 16

Passive require a radio signal to induce current. However active tags contain a small power supply.

Question 17

Describe how a HDD (hardrive) operates.

Answer 17

1. Data is written in concentric tracks which are divided into sectors
2. The reader picks write arm can move across the radius of the disk and the disk can spin
3. This allows the reader to write arm to read and write to anywhere on the disk

Question 18

What are the 2 min downsides of hard drives?

Answer 18

1. They have a lot of mechanical parts meaning they wear overtime.
2. They are susceptible to damage from magnets.

Question 19

How can you increase the storage of a hard drive?

Answer 19

Increase the number of platters
Increase the number of tracks