What is Optics? Study of the behaviour and properties of light How light interacts with matter...

What is Optics?• Study of the behaviour and properties of light

How light interacts with matter Natural occurring optical phenomena and constructed optical

instruments

• Can you think of optical devices that have impacted our lives (medical, scientific, personal)?

• How have each affected science, society, and the environment?

Technologies that use light•Telescope Contacts

•Cameras Magnifying glass

•Microscopes Monocles

•Fiber Optics Binoculars

•Lasers TVs/screens

•Glasses Projector

•and

•Light Sabers

•**Think about which of these you would like to do your presentation on. We will pick 5 together next week**

What is light?• Light is a form of radiant energy that is visible

to the human eye. • Light is a type of electromagnetic wave.• Lights travels in straight lines.• There are natural sources of light such as light

from the sun, stars, fire, and lightening. • Light is produced by some plants and animals. • Artificial light is produced through human

technology. • We need light to see.

Electromagnetic spectrum• Visible light is only a tiny fraction of the

energy that surrounds us every day. • We are surrounded by invisible light-like

waves called electromagnetic radiation.• The entire range of electromagnetic radiation

is called the electromagnetic spectrum.

Electromagnetic radiation is a wave pattern of electric and magnetic fields that can travel through empty space.

In a vacuum, electromagnetic radiation propagates at the speed of light.

Wave Model• A wave is a disturbance that transfers energy

from one point to another without transferring matter, i.e. a water wave

• The movement of energy allows the wave to do work.

• Wave properties:- crest - wavelength- trough - amplitude- rest position - frequency

Period is the amount of time it takes to complete one cycle.Frequency (Hz) is the number of cycles that can

occur in a given time period.

The Wave Equation

• Does this make sense?

• How long would it take light to travel around the world?

fv

White light is colourful• How can white light allow us to see so many

different colours? White light is composed of a combination of all the

colours of the rainbow –the visible spectrum.

• The difference between colours of light is that each colour has a different wavelength and frequency.

Additive Colour Theory of Light

• White light is composed

of different wavelengths

(colours) of light.

• Primary colours of light:

red, green, blue

• Secondary colours of light:

magenta, yellow, cyan

Subtractive Colour Theory of Light

• Coloured matter selectively absorbs different colours (wavelength) of light.

• The colour you see when you look at an object depends on the wavelengths that are reflected. The colours that are absorbed are “subtracted” from the reflected light that is seen by the eye.

• The subtractive theory applied to pigments and dyes.

• Primary subtractive colours: cyan, magenta, yellow

• Secondary subtractive colours: red, green, blue

Producing Visible Light• Natural sources of light

The Sun Stars, fire, lightning Bioluminescence

The ability of a plant or animal to produce light.

• Blue Planet: Amazing and weird creatures exhibit bioluminescence https://www.youtube.com/watch?v=UXl8F-eIoiM

• Natural sources of light The Sun Stars, fire, lightning Bioluminescence

The ability of a plant or animal to produce light.

• Blue Planet: Amazing and weird creatures exhibit bioluminescence https://www.youtube.com/watch?v=UXl8F-eIoiM

Artificial Light pg. 394-399 How does it work?

Where is it used?

Look at efficiency and environmental impacts

1) Incandescent Light pg. 394

2) Fluorescent Light pg. 394

3) Phosphorescent Light and Chemiluminescence pg. 395

4) Triboluminescence and Electric Discharge pg. 396

5) Light Emitting Diode and Organic-light emitting display pg. 397

6) Plasma Displays and Liquid Crystal Displays pg. 398-399

Fun with diffraction grating glasses • Useful for analysing and comparing the light

produced by various sources.

• They function like a prism,

splitting light into its spectrum

component colours.

• Analyse the light from various

sources and compare the

spectra of each.

• See pg. 400

Ray Model of Light • Light is represented as straight lines, which show the direction that light

travels.

• We draw ray diagrams to show the path that light takes after it leaves its course.

• Materials may be classified according to how they transmit, absorb and reflect light: Transparent, Translucent, Opaque

Shadows

Use ray diagrams to help explain the size and location of shadows

Why are some shadows sharp and well defined while other shadows have less distinct edges?

Shadows• A small light source casts shadows that are

sharp and well defined. This area is called the umbra.

• If the light source is

large compared to the

object blocking the light,

a penumbra will form in

the shadow.