Text, sound and images — GCSE Computer Science practice questions

Question 1

A school radio club records interviews with a microphone plugged into a laptop.

What is meant by the sample rate of the recording?

Accepted Answer

B: The number of samples taken each second. The sample rate is how many times per second the amplitude of the sound wave is measured, given in hertz. The number of bits used for each sample is a different setting, the sample resolution.

Question 2

A hiking app shows each photo on a map at the place where it was taken, with the date it was taken underneath. The app finds the place and the date in the photo's metadata.

Which statement about metadata is correct?

Accepted Answer

D: Metadata is data stored with the image that describes it, such as its width, height, date and location.. Metadata is extra data saved in the image file that describes the image: its width, height, colour depth, date and time, GPS location and camera settings. It is separate from the pixel data, so changing it does not change how the image looks.

Question 3

A bus-stop display shows each bus route in its own colour. The city has 40 routes, so the display must be able to show at least 40 different colours.

What is the smallest colour depth that allows this?

Accepted Answer

B: 6 bits. A colour depth of n bits gives 2ⁿ colours. 5 bits give only 32 colours, which is not enough, but 6 bits give 64 colours, which covers all 40 routes. So the smallest colour depth is 6 bits.