Computer science

Question 1

Give me the sizes for units of data:

Answer 1

Bit: 1 or 0
Nibble: 4 bits
Byte: 8 bits
Kilobyte: 1000 bytes
Megabyte: 1000 kilobytes
Gigabyte: 1000 megabytes
Terabyte: 1000 gigabytes
Petabyte: 1000 terabytes

Question 2

Why do overflow errors occur?

Answer 2

Occurs when a number has too many bits.

Question 3

Give me the operation when shifting binary digits to the left and the right.

Answer 3

Left shifts: multiply a binary number for every place shifted to the left, the number is doubled.
Right shift: divide a binary number for every place shifted to the right, the number is halved.

Question 4

What can left shifts and right shifts cause?

Answer 4

Left shifts can cause overflows and right shifts can cause loss of data or its accuracy.

Question 5

What are pixels?

Answer 5

A simple point in a graphical image.

Question 6

What is a bitmap?

Answer 6

Stores each individual pixel.

Question 7

What is color depth?

Answer 7

Number of bits needed to represent each pixel.

Question 8

What is a vector?

Answer 8

The mathematical equation to draw the image.

Question 9

What is the formula to calculate the number of colors using a the color depth?

Answer 9

Total number of colors = 2 to the power of n
n = number of bits per pixel.

Question 10

What is image resolution?

Answer 10

Number of pixels in an image.

Question 11

What happens if the resolution is increased?

Answer 11

The higher the resolution the higher the quality of the image but they also increase file size.

Question 12

What is the formula for resolution?

Answer 12

width x height

Question 13

What is the formula to workout the file size( in bits)

Answer 13

file size (in bits) = image resolution x color depth.

Question 14

What is Metadata?

Answer 14

Metadata is the information stored in an image file which helps the computer recreate the image on screen from the binary data in each pixel.

Question 15

Metadata includes the images :

Answer 15

File format, height, width, color depth and resolution.

Question 16

What would happen without metadata?

Answer 16

Devices would not be able to display the image on screen as intended.

Question 17

What are analogue signals?

Answer 17

Pieces of continually changing data.

Question 18

Why do analogue signals need to be converted?

Answer 18

Analogue signals need to be converted into digital data so that computers can read and store sound files.

Question 19

What device allows analogue signals converted?

Answer 19

Using analogue digital converters.

Question 20

What is sampling?

Answer 20

The process of converting analogue signal to digital.

Question 21

How do we convert analogue signals?

Answer 21

We sample the amplitude of the wave at regular intervals.

Question 22

Relationship between amplitude and bit depth?

Answer 22

Amplitude can only take certain values depending on the bit depth.

Question 23

What are the characteristics of digital data after being converted from analogue signals?

Answer 23

1. Not continuous
2. Lost a lot of data.

Question 24

How can digital data be improved?

Answer 24

By taking samples more regularly.

Question 25

What is sample rate or sampling frequency?

Answer 25

How many samples took in a second.

Question 26

What is the measurement taken for sample rate?

Answer 26

Hz or Hertz

Question 27

What is bit depth?

Answer 27

Number of bits available for each sample.

Question 28

What is the formula to calculate the size of a sound file (in bits)

Answer 28

File size (in bits) = sample rate (in Hz) x bit depth x duration (in seconds).

Question 29

What is data compression?

Answer 29

When we make file sizes smaller while trying to make the compressed file as true to the original as possible.

Question 30

What are the uses of data compression?

Answer 30

1. Takes up less storage space on computers. 2. Streaming and downloading files become quicker as they take up less bandwidth. 3. Allows web pages to load more quickly. 4. Email services usually have restrictions on the size of the attachment you can send. Compressing the file size allows you to send the same content with a much smaller file size.

Question 31

What are the 2 types of compression?

Answer 31

Lossy and lossless

Question 32

What is Lossy compression?

Answer 32

Permanently removes data from the file.

Question 33

What is lossless compression?

Answer 33

Makes the file smaller by temporarily removing data to store the file then it restores it to its original state.

Question 34

What are the pros and cons of lossy compression?

Answer 34

Greatly reduced file size, takes up less band width and commonly used. Loses data, cant be used on text or software files, worse quality but normally unnoticeable.

Question 35

What are the pros and cons of lossless compression?

Answer 35

No reduction in quality, Can be decompressed and turned back to the original, can be used on text and software files. There is only a slight reduction in file size.