Light and OpticsLight and Optics

Optical IllusionsOptical Illusions

visually perceived images that differ from objective reality

3 main types of illusions:- literal illusions - physiological illusions (excessive brightness, colour, size, position, tilt, movement)- cognitive illusions (uncocious inferences)

Physical IllusionsPhysical Illusions

Physiological IllusionsPhysiological Illusions

The orange square on the front of the cube and the brown square on the top of the cube are the same colour

The dots between each square are actually all white, yet when you look quickly from square to square the dots appear black.

Cognitive IllusionsCognitive Illusions

The way you look at an object can affect how you see it. Sometimes there are two images in the same picture, but you can only see one at a time so your brain chooses one (when it deals with too much information)

Electromagnetic Waves Electromagnetic Waves

Energy in the form of a wave-associated with electric and magnetic fields

- can pass through a vacuum or through a medium (glass, water)

What is light?What is light?Form of energy

Converted to electrical energy (solar)

What are some sources of light? (natural or artificial)

Electromagnetic SpectrumElectromagnetic Spectrum

Visible LightVisible Light

Any electromagnetic wave that the human eye can see

Of the Electromagnetic Spectrum, only a small portion is visible to humans

Visible Spectrum - the continuous sequence of colours that make up white light

Electromagnetic Spectrum - the classification of electromagnetic waves, arranged from lowest energy to highest energy

Sources of light…Sources of light…

Natural:- Volcanic (lava)- Lightening- Astronomical Objects(sun, stars, milky way)- Atmospheric Entry (meteors)- Bioluminescence(glow worms, fireflies - chemical (florescent)- fire

Artificial:- candles- gas lighting- lime light- oil lamps

Combination (Electric Powered)- black light- induction lighting- halogen lamps

Incandescence LightIncandescence Light

Production of energy when an object is heated to high temperatures

Example: candles

Flourescent LightFlourescent Light

Produced by an object that has absorbed invisible

radiation(turning UV light to visible light)

Produced by an object that has absorbed invisible

radiation(turning UV light to visible light)

LED (Light-emitting diode)LED (Light-emitting diode)

•When an electric current passes through an LED, it emits light

•More efficient (burn longer, brighter)

•Type of light emitted depends on the material used to make the bulb

Chemiluminescent LightChemiluminescent Light

Production of light from a reaction between 2 chemicals

Example: Glow sticks

Production of light from a reaction between 2 chemicals

Example: Glow sticks

Bioluminescent LightBioluminescent Light

A type of chemiluminescence

The production of light from a chemical reaction within an organism

A type of chemiluminescence

The production of light from a chemical reaction within an organism

QuestionQuestion

What type of light is the moon?

What type of light is the moon?

Non- luminous objectsNon- luminous objects

Do not emit their own light

May reflect light (depending on their surface) and appear to emit itExample: The Moon

Do not emit their own light

May reflect light (depending on their surface) and appear to emit itExample: The Moon

SummarySummary

Light is part of the electromagnetic spectrum

There are numerous sources of light (natural and artificial)

Radiation is the transfer of electromagnetic energy through matter

White light is made up of a spectrum of 7 main colours

Read pages 426-429

Expert Groups:Answer Questions 1-5 pg. 429- 1 group per question- 20 minutes to discuss, read and answer question- each group will inform the class of their answer

Read pages 426-429

Expert Groups:Answer Questions 1-5 pg. 429- 1 group per question- 20 minutes to discuss, read and answer question- each group will inform the class of their answer