1.3 How do computers represent text, images and sound

Question 1

How is text represented in a computer?

Answer 1

Using character sets like ASCII or Unicode.

Question 2

What is ASCII?

Answer 2

A 7-bit code for English letters, numbers, and symbols.

Question 3

What is Unicode and why is it used?

Answer 3

A universal character set for many languages, using more bits.

Question 4

How is sound stored in a computer?

Answer 4

It is sampled at regular intervals and stored in binary.

Question 5

What is sampling rate?

Answer 5

The number of sound samples taken per second (measured in Hz).

Question 6

What is sampling resolution?

Answer 6

The number of bits used to store each sound sample (bit depth).

Question 7

What are bitmap images made of?

Answer 7

Pixels, each stored as binary numbers.

Question 8

What is a JPEG file?

Answer 8

A compressed image file format, used for photos.

Question 9

What is colour depth?

Answer 9

The number of bits used per pixel to represent a color of an image. More bits = more colours.

It is the number of bits that
are used to create each colour in an image

Question 10

What is image resolution?

Answer 10

The number of pixels in an image (e.g., 1920 × 1080).

Question 11

How is image file size calculated?

Answer 11

Resolution × colour depth.

Question 12

How is sound file size calculated?

Answer 12

Sample rate × bit depth × time (×2 for stereo).

Question 13

What is a MIDI file?

Answer 13

Stores music as commands, not actual sound — very small size.

Question 14

What is an MP3 file?

Answer 14

A compressed sound file using lossy compression.

Question 15

What is an MP4 file?

Answer 15

A multimedia file that can store sound, video, images, etc.

Question 16

What is a character set?

Answer 16

When a computer converts text to binary to be processed it uses a tool called a character set.
It contains all the characters that are in that character set and the binary value that is assigned to each character.

Question 17

What are the main character sets that the computer uses?

Answer 17

ASCII and Unicode

Question 18

What are pixels?

Answer 18

Pixel is a very small dot of colour that is displayed with many others to create an
image. An image is made up of pixels.

Question 19

What is RGB system for colors?

Answer 19

Colours are created by computer screens using the Red Green Blue (RGB) colour system.

Question 20

sound sampling

Answer 20

When sound is recorded, this is done at set time
intervals. This process is known as sound sampling.