Topic 3: Units and Data Representation

Question 1

Why must data be stored in binary form

Answer 1

Data must be stored in binary from because in a computer the processor can only recognize 1s and 0s

Question 2

How do you calculate file sizes of sound

Answer 2

sound file size= sample rate x duration x bit depth

Question 3

How do you calculate the file size of an image

Answer 3

image file size = colour depth x image height x image width

Question 4

How do you calculate the file size of a text file

Answer 4

text file size = bits per character x number of characters

Question 5

Where do you find the “most significant bit”

Answer 5

The most significant bit is found on the furthest left as it holds the most value

Question 6

Where do you find the “least significant bit”

Answer 6

The least significant bit is found on the furthest right as it holds the least value

Question 7

What happens when you complete a binary shift to the left once

Answer 7

The number doubles

Question 8

What happens when you complete a binary shift to the left twice

Answer 8

The number doubles twice- quadruples

Question 9

What happens when you complete a binary shift to the right once

Answer 9

The number halves

Question 10

What happens when you complete a binary shift to the right twice

Answer 10

The number divides by two twice causing it to divide by four

Question 11

Carry out a binary shift to the left on 01110101

Answer 11

11101010

Question 12

Carry out a binary shift to the right on 01110101

Answer 12

00111010

Question 13

What is a limitation of ASCII

Answer 13

It only has 7-bit so can only represent 128 characters so can only represent one language

Question 14

What is a limitation of Extended ASCII

Answer 14

This is an additional bit meaning it can represent 256 characters meaning they ca include special characters in different languages however doesn’t account for all global languages

Question 15

Why is unicode better than ASCII and Extended ASCII

Answer 15

Unicode represents over 65000 characters as it has 16-bit. As a result it will account for all global language and symbols

Question 16

If A in ASCII is represented by the code 46 then what is E

Answer 16

50

Question 17

What are digital images made up of

Answer 17

Digital images are made up of pixels. Each pixel is represented by a binary number.

Question 18

What is color depth

Answer 18

To add color, more bits are required for each
pixel. The number of bits determines the range of colors.

Question 19

How do you calculate image size

Answer 19

image height x image width

Question 20

How do you calculate image file size (answer in kilobytes)

Answer 20

(image height x image width x color depth) / 8000

Question 21

What is the resolution of an image

Answer 21

The resolution of an image refers to how tightly packed the pixels are. If an image has a high resolution it tends to a higher file size

Question 22

What is metadata

Answer 22

Information about the file itself

Question 23

What is the sample rate

Answer 23

The number of samples recorded in any given time- measured in hertz

Question 24

What is the duration of a sound file

Answer 24

How long the file lasts

Question 25

What is bit depth

Answer 25

Bit depth refers to the number of bits used to record each sample.

Question 26

How do you calculate the bit rate

Answer 26

sample rate x bit depth

Question 27

What happens in lossy compression

Answer 27

With lossy compression, some data is removed and discarded, thereby reducing the overall amount of data and the size of the file.

Question 28

What happens in lossless compression

Answer 28

With lossless compression, files are reduced in size without the loss of data. However, lossless compression does not usually achieve the same file size reduction as lossy compression.

Question 29

Which type of files would be suitable for lossless compression

Answer 29

Text files, spreadsheets, financial records and emails

Question 30

How do you convert from bits to bytes

Answer 30

8 Bit = 1 bytes

Question 31

How do you convert from bytes to kilobytes

Answer 31

1024 Bytes = 1 Kilobyte

Question 32

How do you convert from kilobytes to megabtes

Answer 32

1024 Kilobytes = 1 Megabyte

Question 33

How do you convert from megabytes to gigabytes

Answer 33

1024 Megabytes = 1 Gigabyte

Question 34

How do you convert from gigabytes to terabytes

Answer 34

1024 Gigabytes = 1 Terabyte

Question 35

How do you convert from terabytes to petabytes

Answer 35

1024 Terabytes = 1 Petabyte