1. Physical Science: Optics
Outcome C2 – Properties of visible light

2. Properties of Visible light
1. Light is a form of electromagnetic energy
It is part of the electromagnetic spectrum
A spectrum is something that can be modelled as continuous

3. Electromagnetic spectrum
What is a spectrum?
“Range” of energies
Microwaves, radio waves, x-rays
Spectrum: where something is not bound to specific values, continual and infinite

4. Properties of Visible light
2. Visible light is also called White light
White light is made up of the visible spectrum
The Visible spectrum are all the colours that are visible to our eyes
The colours:
Red, Orange, Yellow, Green, Blue, Indigo, Violet
The correct mixture of all the colours will produce white light

5. Properties of Visible light
3. Light travels in straight lines 4. Light travels in waves 5. Light waves will reflect and refract

6. Properties of Visible light
Different colours of the visible spectrum have different wavelengths
Longer wavelengths appear Redder
Shorter wavelengths appear Bluer

7. Properties of Visible light
White light can be separated into a spectrum of colours, when passed through a triangular prism
This separation of light is what we see when there is a rainbow

8. Properties of Visible light
Refraction of light – the bending or change in direction of light
this happens when light travels at an angle and passes from one medium to another.
If the medium causes the light wave to slow down, it will bend
Longer wavelengths will bend less
Shorter wavelengths will bend more

9. Properties of Visible light
Reflection of light – when a light wave hits a surface, and bounces off
We see objects as specific colours because the material absorbs all the colours except for the one we see
If no colours are reflected, an object is black. If all colours are reflected, an object is white

10. Properties of Visible light
Ex: An orange is orange coloured because it reflects the colour orange, and absorbs all the other colours
Ex: Mr. Gary’s hair appears black because all the colours are being absorbed and not reflected.

11. Properties of Visible light
FOR HOMEWORK, READ TEXTBOOK PAGE: 299 AND 300 FOR REVIEW

12. Sources of light Luminous objects are things that can emit light
Non-luminous objects are things that only reflect light
Types of light sources:
1. Incandescence – Light coming from hot things
2. Phosphorescence – Light emitted when phosphors release stored energy

13. Sources of light
3. Electric discharge – Light created when electricity passes through gas particles
4. Fluorescence – Light created by one object that is receiving energy from another

14. Sources of light
5. Chemiluminescence – light created when chemical energy is changed into light energy

15. Sources of light
6. Bioluminescence – light created by living things

16. Movement of light waves
Objects have different levels of transparency; they can be transparent, translucent, or opaque.
Transparent material allows light waves to pass through easily
Ex: plastic wrap, glass

17. Movement of light waves
Translucent material allows most light waves through, but blocks some. This results in things looking blurry.
Ex: my water bottle, smudged glass, clouds
Opaque objects block all light waves from passing through
ex: rocks, wood, bricks