Introduction to Light and Optics

What do you already know about light & optics?

What do you want to know?

Click the light bulb to see the concept map for this unit and the candle to see a flow chart for the topics we'll cover

What is light? Click the match to find out

Light is a form of energy (this is the first basic principle of light)

Light is radiant energy that can be transformed into:·electrical energy (photo voltaic cells)·Thermal energy (thermal images)·Chemical energy (photosynthesis)

What are some natural sources of light?

Natural light sources·The sun·Candles or lamps·Wood (fire)·Bioluminescence (light produced by living organisms)

Click on the jellyfish to view a movie about bioluminescence

Name some artificial light sources

Artificial light sources·Incandescentelectrical energy-> thermal energy-> visible light energy·Florescentultraviolet light energy -> absorbed by particles -> visible light energy·PhosporescentLight energy is stored then released·ChemiluminescentChemical energy -> visible light energy

FluorescenceThe long tubes in overhead lights and the tubes that spell the names of stores and restaurants are examples of _______________ light sources. They do not work the same way as _______________ bulbs, which have filaments that heat up and glow.In fluorescent bulbs, _______________energy is absorbed by the particles of mercury _______________ inside the tube. These particles give off _______________ light (a type of light you cannot see), which hits the white _______________ powder on the inside of the bulb. The phosphor particles give off _______________ light.A disadvantage of these bulbs is that they are ______________, so their contents are _______________. An advantage of these bulbs is that they are energy _______________ because they do not get _______________.

efficient electrical expensive fluorescent hot visibleincandescent phosphor poisonous ultraviolet vapour

Phosphorescence

Phosphorescence is similar to fluorescence, except the particles that absorb the _______________ do not release it immediately. There is a _______________. Anexample is a toy ball that _______________ after you hold it near a bright _______________ for a while.

delay

energy

glows

light

Chemiluminescence and Bioluminescence

Electrical and solar energy are used to make incandescent or fluorescent light. Energy released in _______________ reactions provides the energy for chemiluminescence andbioluminescence. Chemiluminescence refers to _______________ light produced this way. Bioluminescence refers to the _______________ produced by _______________ organisms.

artificial

chemical

lightliving

The Cost of Lighting A watt is a unit of electrical power. The cost of light is calculated by how much of the electrical energy is used over a certain period of time. Calculations are made in kW.h (kiloWatt hours)1 kW.h = 1000 watts of electrical energy operating for 1 hour.

What is the cost of leaving a 60W light bulb on for 10 hours 60 W / 1000 = 0.06 kW

0.06 kW x 10 hours = 0.6 kW.h If the cost per kW.h is $0.08, the cost to operate the 60W light bulb for 2

hours would be 0.6 kW.h x $0.08 = $0.048 (4.8 cents – or about 5 cents)

Some facts about Light·Can travel in a vacuum·Travels at high speeds 186,000 miles per second or 3 x 108

m/sec·Travels in a straight line

The Ray Model of LightWhen light interacts with matter it can be:·Reflected (shiny surface like a mirror)·Absorbed (dark surface like asphalt)·Transmitted (light through glass)

Dark objects that absorb radiant energy better that lighter objects will also emit radiant energy more readily

Click on the fox to open the PowerPoint about The Ray Model of Light

Attachments

Light and Optics Unit Map.tif

Sci8 U3 Light&Opticsconcept map.pdf

Introduction_to_Light.asf

Bioluminescence__How_Some_Creatures_Produce_Their_Own_Light.asf

the ray model of light.ppt