Data

Question 1

Why is hexadecimal notation used?

Answer 1

To help humans cope with long strings of binary digits

Question 2

How does 24-bit colour depth represent colours in an image?

Answer 2

Each pixel is represented by three 8-bit numbers (can be simplified to hexadecimal) which represent the amount of red, green and blue

Question 3

What is a character set?

Answer 3

The list of binary codes that can be recognised by the computer hardware and software

Question 4

Define resolution

Answer 4

The number of pixels per inch

Question 5

What’s sound sampling?

Answer 5

Taking digital samples of an analogue waveform at regular fixed intervals

Question 6

What is the bit depth of an audio recording?

Answer 6

The number of bits used to encode each sample

Question 7

How does lossless compression compress?

Answer 7

Looks for redundancy where the same data is stored many times and groups this data as one reference

Question 8

How does lossy compression compress images?

Answer 8

Algorithms analyse the image and find areas with slight difference. They assign these the same value so they can rewrite the file with fewer bits.

Question 9

How does lossy compression compress digital sound recordings?

Answer 9

Very small variations in frequency, tone and volume are removed to reduce file size, as human ears cannot detect these differences

Question 10

How does asymmetric encryption work?

Answer 10

An algorithm called a cipher uses keys to carry out encryption. Every user has two keys. They encrypt the data using the recipients public key, and the data is decrypted using the recipients private key.