Reading RGB values for common colours
Name:
Date:
Class:
A
Quick Questions
Shade in the A or B circle for each question.
1. Which RGB value gives pure red?
2. Which RGB value gives pure green?
3. True or false: (0, 0, 255) is pure blue.
4. What colour do you get by mixing red and green light at full strength: (255, 255, 0)?
5. Which are the three primary colours of light used in RGB?
B
Match the Pairs
Draw a line connecting each item on the left to its match on the right.
| Left column | Right column | |
|---|---|---|
| 1rgb(0, 255, 0) | Argb(0, 0, 255) | |
| 2rgb(255, 255, 0) | Brgb(255, 0, 0) | |
| 3Pure red has red at full strength and green and blue switched off. | CYellow needs red and green on, not blue. It should be rgb(255, 255, 0). | |
| 4Pure blue has only the blue slider turned all the way up to 255. | DThe 255 is in the blue position. Red is the first number, so pure red is rgb(255, 0, 0). | |
| 5rgb(0, 0, 255) for pure red | EPure green: only the green light is on at full strength, red and blue are off. | |
| 6rgb(255, 0, 255) for yellow | FYellow: red and green light are both at full strength and blue is off. |
C
Definitions
rgb(255, 0, 0)
D
Fill in the Blanks
Complete each line of code by filling in the missing parts.
1.
# Pure red
colour = rgb(___, 0, 0)
2.
# Pure green
colour = rgb(0, ___, 0)
3.
# Pure blue
colour = rgb(0, 0, ___)
4.
# Red + green light makes yellow
colour = rgb(255, 255, _)
5.
# Yellow
colour = ___(255, 255, 0)
E
Spot the Error
Shade in the letter of the line that contains an error.
Question 1
A
red = rgb(255, 0, 0)
B
green = rgb(0, 255, 0)
C
blue = rgb(0, 0, 255)
D
yellow = rgb(255, 255, 255)
Question 2
A
set red slider to 255
B
set green slider to 0
C
set blue slider to 0
D
colour is yellow
Question 3
A
red = 0
B
green = 255
C
blue = 255
D
colour = rgb(red, green, blue)
E
show(colour) # pure green
Question 4
A
blue = rgb(255, 0, 0)
B
red = rgb(255, 0, 0)
C
green = rgb(0, 255, 0)
Question 5
A
light1 = rgb(255, 0, 0)
B
light2 = rgb(0, 255, 0)
C
mixed = light1 + light2
D
result = rgb(0, 255, 255)
E
print(result) # yellow
Answer Key
Reading RGB values for common colours
Section A: Quick Questions
Q1
B — (255, 0, 0)
Q2
A — (0, 255, 0)
Q3
A — True
Q4
B — Yellow
Q5
A — Red, green and blue
Section B: Match the Pairs
Q1
rgb(0, 255, 0) → Pure green: only the green light is on at full strength, red and blue are off.
Q2
rgb(255, 255, 0) → Yellow: red and green light are both at full strength and blue is off.
Q3
Pure red has red at full strength and green and blue switched off. → rgb(255, 0, 0)
Q4
Pure blue has only the blue slider turned all the way up to 255. → rgb(0, 0, 255)
Q5
rgb(0, 0, 255) for pure red → The 255 is in the blue position. Red is the first number, so pure red is rgb(255, 0, 0).
Q6
rgb(255, 0, 255) for yellow → Yellow needs red and green on, not blue. It should be rgb(255, 255, 0).
Section C: Definitions
Q1
rgb(255, 0, 0) — Pure red: red at full 255, green and blue at 0. Green is (0, 255, 0), blue is (0, 0, 255), and mixing red and green light makes yellow (255, 255, 0).Section D: Fill in the Blanks
Q1
# Pure red
colour = rgb(255, 0, 0)Q2
# Pure green
colour = rgb(0, 255, 0)Q3
# Pure blue
colour = rgb(0, 0, 255)Q4
# Red + green light makes yellow
colour = rgb(255, 255, 0)Q5
# Yellow
colour = rgb(255, 255, 0)Section E: Spot the Error
Q1
D — Yellow is red and green at full with no blue: rgb(255, 255, 0). Setting blue to 255 as well makes white.
Q2
B — Yellow needs red and green both at 255. With green at 0 the mixer shows pure red, so line 2 should set green to 255.
Q3
C — Pure green is (0, 255, 0), so blue must be 0. With blue at 255 the colour would be cyan.
Q4
A — rgb(255, 0, 0) is pure red. Pure blue has red and green at 0 and blue at 255: rgb(0, 0, 255).
Q5
D — Mixing red light (255, 0, 0) with green light (0, 255, 0) gives (255, 255, 0), which is yellow. (0, 255, 255) is cyan.