WJEC GCSE Digital Technology Data overview quiz quiz

Binary numbers are shorter than decimal numbers

Their electronic components have two states, matching the digits 0 and 1

Humans find binary easier to read than decimal

Binary uses less electricity than other number systems

4

16

8

1024

8

4

32

16

The number of pixels, given as width times height

The number of bits used per pixel

The number of colours in the image

The physical size of the screen in centimetres

40000 bytes

5000 bytes

5000 bits

500 bytes

Reduces the number of pixels in the image

Decreases the file size while improving quality

Allows more colours per pixel but increases file size

Has no effect on quality or file size

Sampling makes the sound louder

Analogue sound contains no useful information

Sampling is only needed for images, not sound

A computer can only store discrete binary values, not a continuous wave

Sample rate x bit depth x length in seconds

Width x height x colour depth

Sample rate x length in seconds, only

Bit depth divided by sample rate

byte, bit, KB, GB, MB, TB

bit, byte, KB, MB, GB, TB

bit, KB, byte, MB, GB, TB

byte, KB, MB, bit, GB, TB

800

128

8000

8

It keeps every bit of the original data

It permanently removes some data, so the original cannot be recovered

It always produces larger files than the original

It only works on text documents

A photograph for a social media post

A streamed music track

A text document where every character must be preserved

A short video clip

Magnetic hard disk drive

Optical CD or DVD

Magnetic tape

Solid-state (SSD or memory card)

It needs an internet connection to access the files

It cannot be accessed from more than one device

It provides no backup of the data

It stores data without using any physical hardware

Compressed images always look better than originals

Compression increases the resolution of the images

Smaller files download faster and use less bandwidth

Compressed images cannot be copied by visitors