Grade 8 ScienceColours

How was light discovered?

In the seventeenth century, Sir Isaac Newton placed a prism so that a thin beam of light could pass through it. When the white light passed through the prism, bands of colour emerged from the other side. This is because different colours will refract at different angles producing a rainbow effect.

Dispersion of White Light

From Coloured Light back to White Light

Colors

The Colour Spectrum

When white light refracts into different colors, the result is called a spectrum. The colours that form the spectrum are:

- Red- Orange- Yellow- Green- Blue- Indigo- Violet

Place your finger in between the two blocks. What do you see?

Additive Primary Colours

The three additive primary colours are red, green, and blue

How to create other colours

Using the three additive colours in proper amounts, you can create the three secondary colours: Yellow, Cyan and Magenta

Subtractive Primary Colours

The three subtractive primary colours are Yellow, Magenta, and Cyan

How to create other colors

Using the three subtractive colours in proper amounts, you can create the three secondary colours: Red, Green, Blue

What are the differences and similarities

How many cells are in our retina?

Answer

2

The Rods and Cones

Rods - Rods detect the presence of light

Cones - Cones detect colour

Cones

There are three types of cones in our retinas

The first type of cones respond to light of long wavelengths

The second type of cones respond to light of medium wavelengths

The third type of cones respond to light of short wavelengths

Colour Blindness

Although white light contains red, orange, yellow, green, blue, indigo, and violet light, cones in the human eye responds mostly to red, green, blue light.

Cone cells in some people’s eyes are unable to detect certain colours resulting in colour blindness