Section 4 - Data Representation

Question 1

Describe how binary is used to represent data in computers

Answer 1

Computers are made up of logic circuits which use high and low voltages to represent 1s and 0s.

Question 2

Define the term ‘character set’

Answer 2

A character set is a collection of characters a computer recognises from their binary representation.

Question 3

Convert the hexadecimal 4E into decimal

Answer 3

78

4×16 = 64, 64+14 =78

Question 4

Define the term ‘image resolution’

Answer 4

The size of an image (width × height) in pixels.

Question 5

Describe how the number of bits used per pixel affects the colours in an image.

Answer 5

The number of bits per pixel determines the number of possible colours and so increases the amount of unique colours an image has available to use.

Question 6

Explain why compression is used for audio files

Answer 6

Audio files can be very large especially for long podcasts. Compression is used to reduce the overall size of the audio file with some acceptable loss of quality.

Question 7

What type of compression is Huffman coding?

Answer 7

Lossless

Question 8

Explain how increasing the sampling rate can affect the quality of the sound file.

Answer 8

Increasing the sampling rate means that more samples are taken every second. The sound quality will be better as the file will more closely match the original.

Question 9

What is the hexadecimal representation of the letter P?

Answer 9

50

Binary = 01010000, split into nibbles = 5 and 0 which = 50