1.2 Units and Data

Question 1

What are two ways of storing images in binary?

Answer 1

Bitmap and a vector

Question 2

What is made from a bitmap?

Answer 2

An image made up of different coloured squares, (pixels) each having a binary value

Question 3

What is made from a vector?

Answer 3

The mathematics to store the square are stored e.g. a circle can be drawn just by storing the details of X and Y coordinates from the middle, the radius, the width and colour

Question 4

What is stored as a bitmap?

Answer 4

Photographs not made up of simple shapes

Question 5

What is stored as a vector?

Answer 5

Technical drawings, logos and clipart

Question 6

What is metadata?

Answer 6

Additional data is stored along with the image to define the width, height, colour depth, and palette. (It allows the computer to take the binary raw data and make the correct resolution image)

Question 7

The greater the colour depth and resolution…

Answer 7

the larger the file size of the image

Question 8

What is each pixel of a bitmap stored in?

Answer 8

Binary

Question 9

The number of bits required for each pixel depends on …

Answer 9

Number of colours required
e.g. 1 bit has 2 values: black and white
2 bits have 4 possible values : 00,01,10,11. Therefore 2 bits can store 4 colours

Question 10

How is number of colours calculated?

Answer 10

2^n where n is the number of bits for each pixel

Question 11

What are photographs stored in?

Answer 11

24-bit colour depth, Each pixel is 2 bits. This is 2^24 = over 16 million colours. The number of different colours the human eye can see

Question 12

What is sound?

Answer 12

A vibration that propagates as an audible wave of pressure through the air.

Question 13

What is analogue to digital conversion?

Answer 13

Convert what is an analogue signal into a digital binary one.

Question 14

What affects quality of a digitally converted sound wave?

Answer 14

Sample rate (speed)
Bit depth (detail)

Question 15

What is sample rate?

Answer 15

How often per second we are sampling the original analogue sound (record the amplitude of a sound wave). - number of samples stored per second)

Question 16

What is the bit depth?

Answer 16

The amount of detail we are capturing with each sample (number of bits stored per sample)

Question 17

What happens when you record a sample more often?

Answer 17

The more often you record a sample the smoother the playback will sound.

Question 18

The higher the number of samples per second,

Answer 18

The higher the quality the sound will be but also the larger the file size, as we are storing more data per second.

Question 19

What is the sound file size?

Answer 19

The total number of bits in a sound. Calculated as (number of samples per second) x (number of bits per sample) x (length of sample in seconds)

Question 20

The higher the number of bits,

Answer 20

the greater the quality of the sound and the larger the file size

Question 21

Duration

Answer 21

how many seconds of audio the sound file contains

Question 22

What does compression do?

Answer 22

Reduces number of bits in a file making storage capacity of the file lower and making data transfer useful.

Question 23

Why is compression useful?

Answer 23

More data can be stored on a storage device and transferred in a smaller amount of time.

Question 24

What happens in lossy compression?

Answer 24

• Some of the data is lost and cannot be recovered.
  This greatly reduces file size and the quality of the image/sound.
• It is suitable for images, sound, video
• Cannot be used on text and executable files.

Question 25

What happens in lossless compression?

Answer 25

• None of the data is lost, it is encoded differently.
• Can be turned back into digital format and can be used on all types of data.
• Usually less effective than lossy compression at reducing the file size
• Most suitable for documents and executable files.

Question 26

What is standalone computers?

Answer 26

Computers that are not connected to any network

Question 27

Advantages:

Answer 27

Users can share files, peripherals - printers and connections to other networks e.g. Internet
- Users can access files from any computer on the network
- Servers can control security, software updates and backup of data.
- Communication with other people e.g. email and social networking

Question 28

What is LAN?

Answer 28

LAN, also known as Local Area Network, covers a small geographical area located on a single site. All hardware for a LAN is owend by organisation using it.

Question 29

What are LANS wired?

Answer 29

They are wired with UTP cable, fibre optic, or wireless using WIFI

Question 30

What is WAN?

Answer 30

WAN, also known as Wide Area Network, covers a large geographical area, connecting LANS together.
- The infrastructure between LANS is leased from telecommunication companies who own and manage it.
- WANS are connected with telephone liner, fibre optic cables or satellite links

Question 31

What are these networks connected with?

Answer 31

Computers in a local area network are connected with a switch
- Computers in a wide area network are connected with a router

Question 32

Disadvantages of networking

Answer 32

• Increased security risks to data
• Malware and viruses spread very easily between computers
• If a server fails, the computers connected to it may not work
• The computer may run more slowly if there is a lot of data travelling on the network