Chapter 5 - Input devices

Question 1

What do 2D scanners do?

Answer 1

they convert hard-copy documents into an electronic form

these can be stored in a computer memory

Question 2

How do 2D scanners work?

Answer 2

A scan head moves across the document producing an image
this is sent to a lens via a series of mirrors
the focused image falls on a charge-coupled device (CCD) which consists of a number of integrated circuits
the original document is turned into a format that can be stored in a computer’s memory

Question 3

What are applications of 2D scanners?

Answer 3

at airports to read passports

Question 4

What do 3D scanners do?

Answer 4

scan solid objects and produce an electronic 3D image

Question 5

How do 3D scanners work?

Answer 5

They use lasers/x-rays

Question 6

What are CT 3D scanners used for?

Answer 6

to produce a 3D image of a solid object

Question 7

How does tomography technology work?

Answer 7

splits up the object into a number of thin slices
use x-rays, radio waves or gamma imaging methods
the resultant image allows a solid object to be stored as a series of digital values representing each slice

Question 8

What do barcodes consist of?

Answer 8

a series of light and dark lines of varying thickness (representing each digit or character)

Question 9

Where are barcodes used?

Answer 9

supermarkets

Question 10

What are the advantages of barcodes for managers?

Answer 10

easier and faster to alter prices
give instantaneous and comprehensive sales trends
no need to price each item
allows automatic stock control
can check customer’s buying habits more easily

Question 11

What are the advantages of barcodes for customers?

Answer 11

faster checkouts
less chance of errors
get an itemised bill
cost savings can be passed on to the customer
better tracking of sell-by dates

Question 12

What are QR codes?

Answer 12

a type of barcode

hold considerably more data than barcodes

Question 13

How are QR codes read?

Answer 13

by built-in cameras in smartphones or tablets

sends information back to the phone or tablet

Question 14

What do the microprocessors in digital cameras do?

Answer 14

adjusts shutter speed
focuses
operates the flash
adjusts the aperture
removes red eye
reduces handshake

Question 15

How are images captured on a digital camera?

Answer 15

light passes through the lens onto light-sensitive cells - made up of thousands of tiny elements called pixels
the number of pixels determines the size of the file needed to store the image

Question 16

How do keyboards work?

Answer 16

keys are pressed by the operator to enter data directly into the computer
when a key is pressed it completes a circuit and a signal is sent to the microprocessor which interprets which key has been pressed

Question 17

Why do most computer systems use a keyboard buffer?

Answer 17

entering data by a keyboard is a slow process

prevents the microprocessor from waiting for keys to be pressed

Question 18

What are the health risks posed by typing?

Answer 18

RSI - repetitive strain injury

Question 19

What are the most common pointing devices?

Answer 19

mouse and the trackerball

Question 20

What do pointing devices control on screen?

Answer 20

a cursor to select options from menus

Question 21

Which out of a mouse and a trackerball poses less health issues?

Answer 21

trackerball (do not get RSI as you don’t have to repeatedly click a mouse button)

Question 22

What are microphones used for?

Answer 22

to input sound into a computer

Question 23

How does a microphone work?

Answer 23

when picking up a sound:
a diaphragm vibrates producing an electric signal
a sound card in the computer converts the signal into digital values which can be stored in its memory

Question 24

How does speech recognition use microphones?

Answer 24

speech recognition:
works by converting speech patterns into a digital form (broken into phonemes which are compared to words in a built-in dictionary), spoken word then recognised

Question 25

How does voice recognition use microphones?

Answer 25

voice recognition:
used to identify if a ‘known’ person is speaking (such as in a security system), the software compares the wave patterns from the voice with wave patterns stored in memory

Question 26

What do touchscreens do?

Answer 26

allow selections to be made by simply touching an icon or menu option on a screen

Question 27

What are the 3 main types of touchscreens?

Answer 27

capacitive, infra-red, resistive

Question 28

How do capacitive touchscreens work?

Answer 28

uses layers of glass that acts as a capacitor
when the top layer is touched, the electric current changes
microprocessor works out the coordinates of where the screen was touched

Question 29

What are the benefits of capacitive touchscreens?

Answer 29

medium-cost technology
good visibility in strong sunlight
allows multi-touch capability
very durable

Question 30

What are the drawbacks of capacitive touchscreens?

Answer 30

can only use bare fingers/conductive stylus

Question 31

How do infra-red touchscreens work?

Answer 31

uses glass and can either detect heat or uses infra-red sensors to detect touch
microprocessor works out where the screen was touched based on sensor/heat data

Question 32

What are the benefits of infra-red touchscreens?

Answer 32

allows multi-touch capability
can use bare fingers, gloved hand or stylus
good screen durability

Question 33

What are the drawbacks of infra-red touchscreens?

Answer 33

relatively expensive technology

heat-sensetice systems only allow bare fingers to be used

Question 34

How do resistive screens work?

Answer 34

uses an upper layer of polyester and bottom layer of glass
when the top layer is touched, it completes a circuit
microprocessor works out the coordinates of where the screen was touched

Question 35

What are the benefits of resistive screens?

Answer 35

relatively inexpensive technology

can use bare fingers, gloved hand or stylus

Question 36

What are the drawbacks of resistive screens?

Answer 36

poor visability in stong sunlight
doesn’t allow multi-touch capability
screen vulnerable to scratches

Question 37

What do sensors do?

Answer 37

send data from the real world to a computer

Question 38

What type of convertors do you need for sensors to convert real world data into data which the computer can understand

Answer 38

anaolouge to digital converter (ADC)

Question 39

What type of systems do sensors form a part of?

Answer 39

monitoring or control systems

Question 40

What does monitoring mean?

Answer 40

reports the status of a system via a computer/microprocessor

Question 41

What does control involve?

Answer 41

altering devices so that the output affects the next input to the computer

Question 42

What are the different types of sensors?

Answer 42

temperature
moisture/humidity
light
infra-red
motion
pressure
acoustic/sound
gas
pH
magnetic field

Question 43

What are examples of monitoring systems?

Answer 43

montioring a patients vitals in hospital
burgular/intruder alarm systems
monitoring pollution levels in the air
checking key data in a car engine

Question 44

What are examples of control systems?

Answer 44

traffic light control
greenhouse environment
street lighting
anti-lock braking system
control of a chemcial/nuclear process

Question 45

What are interactive whiteboards?

Answer 45

allows computer images to be displayed using a digital projector
allow users to write on the whiteboard and the text/images created to be stored in computer memory

Question 46

What is an input device?

Answer 46

hardware that allows a computer to receive data from the outside world