Light and Optics

Optical 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)  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 Illusions

Physiological Illusions FThe orange square on the front of the cube and the brown square on the top of the cube are the same colour

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

Cognitive Illusions FThe 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 FEnergy 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? FForm of energy FConverted to electrical energy (solar) FWhat are some sources of light? (natural or artificial) FForm of energy FConverted to electrical energy (solar) FWhat are some sources of light? (natural or artificial)

Electromagnetic Spectrum

Visible Light FAny electromagnetic wave that the human eye can see FOf the Electromagnetic Spectrum, only a small portion is visible to humans FAny electromagnetic wave that the human eye can see FOf the Electromagnetic Spectrum, only a small portion is visible to humans

FVisible Spectrum - the continuous sequence of colours that make up white light FElectromagnetic Spectrum - the classification of electromagnetic waves, arranged from lowest energy to highest energy FVisible Spectrum - the continuous sequence of colours that make up white light FElectromagnetic Spectrum - the classification of electromagnetic waves, arranged from lowest energy to highest energy

Sources of light… FNatural: - Volcanic (lava) - Lightening - Astronomical Objects (sun, stars, milky way) - Atmospheric Entry (meteors) - Bioluminescence (glow worms, fireflies - chemical (florescent) - fire FArtificial: - candles - gas lighting - lime light - oil lamps FCombination (Electric Powered) - black light - induction lighting - halogen lamps

Incandescence Light FProduction of energy when an object is heated to high temperatures Example: candles

Flourescent Light FProduced by an object that has absorbed invisible radiation (turning UV light to visible light)

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 Light FProduction of light from a reaction between 2 chemicals Example: Glow sticks FProduction of light from a reaction between 2 chemicals Example: Glow sticks

Bioluminescent Light FA type of chemiluminescence FThe production of light from a chemical reaction within an organism FA type of chemiluminescence FThe production of light from a chemical reaction within an organism

Question FWhat type of light is the moon?

Non- luminous objects FDo not emit their own light FMay reflect light (depending on their surface) and appear to emit it Example: The Moon FDo not emit their own light FMay reflect light (depending on their surface) and appear to emit it Example: The Moon

Summary FLight is part of the electromagnetic spectrum FThere are numerous sources of light (natural and artificial) FRadiation is the transfer of electromagnetic energy through matter FWhite light is made up of a spectrum of 7 main colours FLight is part of the electromagnetic spectrum FThere are numerous sources of light (natural and artificial) FRadiation is the transfer of electromagnetic energy through matter FWhite light is made up of a spectrum of 7 main colours

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