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Computer Science > 3.2 Inputs and Outputs > Flashcards

3.2 Inputs and Outputs Flashcards

1
Q

what are input devices

A

devices that allow you to pass information from the real world into a computer system

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2
Q

how does a barcode scanner scan

A

a red light illuminates the barcode, the white lines reflecting more light where the black lines absorb some light and reflect less, the microprocessor within the scannner detects this difference of light intensity and converts it into a binary value

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3
Q

what are barcodes typically used for (3)

A

scanning groceries
scanning books
scanning packagaes for delivery

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4
Q

why are barcodes required

A

less error by manual input
quicker data input
more detailed tracking info
automatic

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5
Q

how do digital cameras work

A

as light enters the camera, the light falls onto a lens filled with millions of tiny squares called pixels, each pixels measures the light intensity and converts these into digital values displaying colours

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6
Q

why are digital cameras used (3)

A

luxury, intergrated in nearly all smartphones
photogrophares use dedicated high end cameras
for cctv surveilance

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7
Q

why are digital cameras required

A
  • easy photography, no development required
  • digital photos can be easily transmitted via bluetooth or wifi
  • replaced film based cameras
  • embedded software can change photos easily, retouch, anti red eye, filters
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8
Q

how do keyboards work

A

each key has a character value, key presses send signals to the computer which it interprets and displays the correct character on the screen

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9
Q

how do optical mouses work

A

the mouse has a sensor and red LED below the mouse, the sensor detects the movement relative to the surface beneath and the computer replicates the speed and distance by moving a cursor

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10
Q

how to microphones work

A

soundwaves cause a coil to move around a magnet causing electrical field changes, these small changes are detected by a microproccessor and and ADC (ananlog to digital converter) and converted into a digital sound representation

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11
Q

how do QR codes work

A

QR stands for quick response, it is read my a camera and an app then processes the images and converts it into readable data

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12
Q

what is the advantage of QR codes over Barcodes

A

QR codes can hold more data 7089 digits
whereas barcodes hold lesss, 30digits

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13
Q

what are the 3 types of touchscreen

A

resistive
capacitive
infrared

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14
Q

how do resistive touchscreens work

A

2 layers where the upper layer is flexible polyester materials, inbetween the 2 layers there is a non conductive gas. when the top layer is pressed it touches the bottom layer, completeing a circuit

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15
Q

how do infrared touchscreens work

A

LED shines infrared light accross the screen, forming a matrix, when the screen is touched the beams are interrupted, the touch is recognised

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16
Q

how do capacitive touchscreens work

A

compound protective layer. under that theres a conductive layer, and undethat a glass substrate, touching the screen with bare hands or a special stylus changes the electrostatic field of the conductive layer

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17
Q

what are the advantage of resistive touchscreen (3)

A

can be worked with a gloved hand, hand and stylus
cheap to produce
resistant to surface contaminants

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18
Q

what are the disadvantage of resistive touchscreen

A

image clarity and precision is not good

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19
Q

where are resistance touchscreens used

A

cash machines, kiosk for info (mcdonalds) and medical equipment

20
Q

what are the advantage of capacitive touchscreen (4)

A

excellent image clarity
high precision
durable screen
allow multiple touches at the same time

21
Q

disadvantage of capacitive touchscreens

A

requires bare finger or stylus

22
Q

what are advantages of infrared touchscreens

A

excellent image display, unlimited touchlife

23
Q

disadvantage of infrared touchscreens

A

sensitive to ambient light and water snow etc

24
Q

where are infrared touchscreens used

A

very large scale screens at companies, concenrts, maybe used for info kiosks and med equipment

25
how do 2D scanners work
shines a bright light onto the scanned document to measure the amount of light reflected and create a digital document
26
how do 3D scanners work
shines a laser onto the object to measure the variations in dimensions and record the geometry
27
what are 2D scanners used for
scanning documents in companies and government
28
what are the 8 outputs to know about
actuators LED screens LCD projector/screen speakers 3D printer Laser printer Inject printer Digital light processing projector
29
what is an actuator
every actuator is purpose built however they all essentially have one purpose, to carry out a physical movement
30
what are actuators used for
stopping starting pump devices opening closing automatic doors turning a wheel opening closing a valve starting and stopping a conveyer belt operating an aircrafts wing flaps
31
how do DLP projectors work
DLP systems use millions of micro mirros arranged in a matrix grid and placed on a small microchip within the projector, white light is then shone through a rotatig colour filter to produce the image while an angled mirro changes the colour intensity
32
what are the advantages of DLP over LCD projectors
higher contrast ratios smoother video smaller lighter, portable better suited for dusty or smokey atmospheres
33
how do LCD projectors work
use 3 mirror filters to seperate an image into red green and blue wavelengths. These images are then passed through a prism and recombined to project
34
advantages of LCD over DLP
sharper image better colour reporduction typically less expensive quieter operation lower power usage and heat production
35
how do inkject printers work
inkjet printers force ink out of tiny nozzles onto a peace of paper to replicate a digital document or image
36
what are inkjet printers used for
small scale printing usually cheaper and smaller so for personal use
37
why are inkjet printers required
even today hard copies are required for information storage other than digital, they can be looked at without internet
38
how do laser printers work
laser printers use toner cartridges filled with powerdered, electro optically charged ink, lasers create a mirro image of the printer page onto a drom creating negatively charged areas, the drum picks up the positively charged ink particles and bonds them to the paper using heat
39
what are laser printers typically used for
very fast and accurate for non colour documents has a low running cost per paper rather than inkjet high quality inexpensive printing
40
how do LCD screens work
a screen made up of millions of tiny liquid crystals, these form a matrix of pixels which can be changed through electrical field changes, usually require some form of backlighting to work such as an LED or flourescent lamp
41
how do LED screens work
bunch of tiny light emitting diodes which can display instantly rather than needing any additional backlighting
42
why is LED better than LCD (4)
because it has better image quality longer lifespan no need for additional backlighting so can be thinner multiple LEDs can be joined togethor making big screens for concerts etc
43
how do speakers work
the digital representation of the sound is sent to a digital to analogue converter DAC which can be further boosted by an amplifier before being send to the speakers
44
how do 3D printers work
a mix of laser and inkject technology, the 3D printer deposits layers of material ontop of eachother to create a 3D object, matieral can be plastic, resin or anything else
45
what are 3D printers used for (3)
rapid prototyping personal items mznufacturing
46
why do we need 3D printers
allows us to create virtually created objects into real life objects for manufacturing which can be quick and with minimal waste and labour

Computer Science (8 decks)

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