Transcript Unit 3: Light and Optics The unit goal:

Unit 3: Light and Optics
The unit goal:
We have been commissioned by the Telus
Spark to develop exhibits that allow our
visitors to experiment, try things, build
things and play.
Our exhibits will use the concepts of light
and optics that we will study over the next 3
weeks.
The grade 8’s will create a science center for
the grade 5’s, and then open it up to the
community.
The unit goal:
It takes a core set of skills to create something new, whether
it’s a groundbreaking discovery or a toy robot. At MCMS Spark,
we want to invite our visitors to hone their skills: use
imagination to see beyond what exists, curiosity to formulate a
question and persistence and problem-solving skills to take a
risk, and to keep going and growing confidence.
We don't just relay information; we are a role model and force
for innovation that drives positive change, we’re here to
provide the tools to empower visitors to engage in the process
of science -MCMS Spark’s goal is to help visitors engage in the
process of science and inspire people to ask questions and seek
out answers through investigation and reflection.
Our participatory exhibits are designed to encourage visitors, from
children to adults, to pursue new ways of discovering the science
behind light and optics and the ways in which this science
improves our world or solves a problem.
Our goal is to create exhibits that encourage the following in our
visitors
•Engagement
•Creation of conversation and new ideas
•Creativity and Innovation
•Collaboration
•Risk Taking
•Problem Solving
Adapted from Telus spark
Watch this video:
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Light and Optical Systems
Science 8: Unit 3
Topic 1, Lesson 1: What is light?
I can:
•Define Light
•Identify types and sources of light
What is Light?
energy
see
• Light is the form of ______that
you can_____
• Light is all around us
What inventions use light?
Can you think of more than Mrs. D did? She got 9
• Light bulbs/flashlights
• Infrared remote controls
• Microwave oven
• Lasers
• Camera
• Eye glasses
• Microscope/telescope/binoculars
What will we learn in this unit?
•
What is light?
•
How does light behave?
•
Geometric Ray Model
•
Reflection (in different types of lenses)
•
Refraction (through different mediums)
•
Light-based technology that extends our vision
•
•
binoculars, telescopes, microscopes
Color
•
•
spectrum, primary colors
What kind of energy comes from light?
•
Radiant energy
•
Infrared, radio, ultraviolet, X rays, gamma rays
•
How does light travel?
•
The Wave Model
Think of some natural light sources:
(i.e. NOT man made)
• The sun
• stars
• fire
• sparks
The Sun’s Energy
• How does light spread out from the
sun?
• it radiates in all directions
• What does that look like?
The Sun’s Energy con’t
• Energy transfer that does not require
matter is called radiation.
• Energy/light that travels by radiation is
called radiant energy.
Cool fact
• Less than one tenth of one millionth of a
percent (1/10 000 000% or 0.000 000 01%) of
the sun’s rays actually reach us on earth.
What would we do without you?
• Why are we totally dependent on the sun’s
energy?
• it is our largest natural light source
• it keeps us warm
• it lets plants (producers) carry out
photosynthesis
• continues the oxygen cycle
• we (consumers) eat plants.
• No plants = no food!
When the sun is asleep...
• We use artificial lights
• Do these lights have energy?
• If so, they should be able to cause
changes in matter...
What would happen if...
...we placed a black piece of paper under a lamp
for a few minutes?
It heats up!
Can you think of some real-life examples of light
changing to heat?
What would happen if... It’s a sunny day and you...
•Wear a black shirt
•Sit on dark upholstery in a car
1st principle of light:
•
Light is a form of....
Energy!
•
When it is absorbed by a surface, it can be transformed
into several forms of energy
•
thermal energy (heat)
• i.e. temperature rises
• electrical energy
• i.e. solar powered calculator
• chemical energy
• i.e. during photosynthesis
Sources of light
• Imagine if we had no artificial light...
• We wouldn’t have:
•
•
•
•
•
TV
computers
lamps
theatre lighting
life after dark!
The sources of light
Let’s look at the sources of artificial light...
Fill the information into your chart
Incandescent Source
• What is it?
• When something gets so hot that it gives off
visible light
•
•
ever touched an old-style light bulb and gotten burned?
Energy transformation:
Electrical Energy --> Thermal Energy --> Visible Light Energy
•
95% of the energy given off by an incandescent
light bulb is released as HEAT.
Fluorescent Sources
• What is it?
• High energy UV light is absorbed by
particles
• The particles emit this energy as visible
light.
This ‘glow’ is called fluorescence
• Energy transformation:
Electrical energy -->Ultraviolet light Energy -->
Energy absorbed by particles --> Visible Light Energy
Fluorescent tubes
Look at the next page in
your handout
•filled with mercury vapour.
•an electric current stimulates the vapour, causing it to give off UV rays
•UV rays are absorbed by the particles in the phosphor coating
•causes the coating to glow --> and we have light.
Benefits?
•energy efficient (less energy wasted as heat)
Phosphorescent Sources
• What is it?
• Similar to fluorescent:
• Particles absorb light energy, but they can
store it for a while.
• The result?
• Glow-in-the-dark!
Chemiluminescent Sources
• What is it?
• Chemicals mix, react, and give off visible
light
•
•
In the glow stick:
•
2 chemicals are kept separated by a barrier.
•
Break the barrier by bending the stick
•
the chemicals mix --> chemical reaction that emits visible
light
Energy transformation:
Chemical Energy --> Visible Light Energy
Bioluminescent Sources
• What is it?
• An animal has a chemical reaction inside
its body that causes it to emit visible light
• Examples?
•
Some fish/jellyfish: To attract prey & warn off predators
•
fire flies: To attract a mate
•
fungi in caves
Do you get it?
With your table group, brainstorm more examples
of each source of light
Add your examples to your table.