2.5 Data Representation

Question 1

What is the order of data size?

Answer 1

Bit - single digit (0 or 1)
Nibble - 4 bits 
Byte - 8 bits 
Kilobyte - 1024 bytes 
Megabyte - 1024 KB 
Gigabyte - 1024 MB 
Terabyte - 1024 GB 
Petabyte - 1024 TB

Question 2

How do computers understand binary?

Answer 2

They don’t understand the numbers 1 and 0, they understand flashes of electricity that pass through the transistors.
1 = Electricity pulse
0 = No electricity pulse

Question 3

What number system is binary?

Answer 3

Base 2:

2 possibilities - 1 or 0).

Question 4

Define vector

Answer 4

An image drawn by a set of mathematical formulas and can be scaled infinitely without any loss in quality.

Every line and shape has a value that changes when the image expands.

Question 5

Define bitmap

Answer 5

Page is divided into an invisible grid and each pixel is assigned a colour in binary (colour depth).

Higher bit depth = Higher image quality.

Question 6

What is PPI and DPI?

Answer 6

Pixels per inch.

Dots per inch.

Question 7

What happens if a pixel is to represent more than 1 colour?

Answer 7

We need to use more bits to make a range of colours available.

Question 8

How do you find out how many bits represent colours?

Answer 8

2 to the power of the number of bits = number of colours.

1 bit = 2 colours.
2 bits = 4 colours.
3 bits = 8 colours.

Question 9

What happens with greater colour depth?

Answer 9

The more:
Realistic colours there are
Data needs to be stored.
File size on the disk is needed.

Question 10

What happens with higher resolution?

Answer 10

There are more pixels, higher quality and higher image file size.

Question 11

What is digital sound broken down into?

Answer 11

Thousands of samples per second - each of which are stored as binary data.

Question 12

What does the quality of the samples depend on?

Answer 12

1) Sample frequency.
2) Sample size / bit depth.
3) Bit rate.

Question 13

Define sample rate

Answer 13

No. of audio samples captured every second.

Question 14

Define analogue

Answer 14

Made up of a variation of dynamic and frequencies.

Question 15

Define sampling

Answer 15

Recording snippets of sounds at set intervals.

Question 16

Define character set

Answer 16

The possible characters that can be represented in a computer system.

E.g. ASCII and Unicode.

Question 17

Define metadata

Answer 17

Image data that allows the computer to recreate the image from the binary data in the file.

Examples: 
Dimensions. 
Number of bits per pixel. 
Location. 
Data and File type.

Question 18

Define image size

Answer 18

Width and height of a bitmapped image, measured in pixels.

Question 19

If an image has its colour depth increased what is the effect?

Answer 19

The file size is bigger.

Question 20

Define overflow error

Answer 20

When the binary number is too big than actually possible

Question 21

What are the hexadecimal numbers compared to denary numbers?

Answer 21

A = 10
B = 11 
C = 12 
D = 13 
E = 14 
F = 15

Question 22

Define lossy compression

Answer 22

The file is compressed and data is lost. It compresses more than lossless

Should be used in audio files.

Question 23

Define loseless compression

Answer 23

The file is compressed; no data has been lost (file size is just smaller, but it isn’t as compressed as lossy ).

Should be used in text documents.

Question 24

What is the effect of multiplying the binary number by 2?

Answer 24

The number is shifted to the left by 1 bit

Question 25

What is the effect of dividing a binary number by 2?

Answer 25

The number is shifted to the right by 1 bit

Question 26

Define underflow

Answer 26

When the binary number is too small than actually possible