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Laws of Light
Light energy has predictable properties when it interacts with matter
that we refer to as reflection and refraction. In this workshop we
will explore what happens to light when it strikes a smooth surface,
a rough surface, or a transparent surface.
In particular, we will examine
several big ideas about light through viewing demonstrations with
light and mirrors, visiting an artist and an astronomer who use mirrors
in their work, watching fifth grade students investigate refraction,
and listening to experts talk about light. We will also ask you to
think about some situations involving reflection and refraction.
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Learning Objectives
Participants will understand that:
- Light energy can be absorbed, reflected, and refracted by matter.
- Light energy is reflected off objects at a predictable angle. The
angle of the incoming light equals the angle of the outgoing light.
This is called the law of reflection.
- Light energy reflects off smooth and rough surfaces following the
law of reflection. Rough surfaces create a scattering of the photons,
which prevents us from seeing images.
- Light energy changes speed (and thus direction) when crossing the
boundary between two different transparent materials in a process
called refraction.
- The refractive property of transparent materials can be used to
make lenses that focus light (e.g., cameras, eyeglasses, telescopes).
Standards
National Science Education Standards
K-4 Standards:
- Light travels in a straight line until it strikes an object. Light
can be reflected by a mirror, refracted by a lens, or absorbed by
the object.
Content Standards: K-4: Physical Science: Light, Heat, Electricity,
and Magnetism
- Scientists develop explanations using observations
(evidence) and what they already know about the world (scientific
knowledge). Good explanations are based on evidence from investigations.
Content Standards: K-4: Science as Inquiry: Understandings About
Scientific Inquiry
5-8 Standards:
- Energy is a property of many substances and is associated with heat,
light, electricity, mechanical motion, sound, nuclei, and the nature
of a chemical. Energy is transferred in many ways.
Content Standards: 5-8: Physical Science: Transfer of Energy
- Light
interacts with matter by transmission (including refraction), absorption,
or scattering (including reflection). To see an object, light from
that object— emitted by or scattered from it —
must enter the eye.
Content Standards: 5-8: Physical Science: Transfer of Energy
K-12 Standards:
- Although most things are in the process of becoming different —
changing — some properties of objects and processes are characterized
by constancy, including the speed of light, the charge of an electron,
and the total mass plus energy in the universe. Changes might occur,
for example, in properties of materials, position of objects, motion,
and form and function of systems. Interactions within and among
systems result in change.
Content Standards: K-12: Unifying Concepts and Processes: Constancy,
Change, and Measurement
- Models are tentative schemes or structures
that correspond to real objects, events, or classes of events, and
that have explanatory power. Models help scientists and engineers
understand how things work. Models take many forms, including physical
objects, plans, mental constructs, mathematical equations, and computer
simulations.
Content Standards: K-12: Unifying Concepts and Processes: Evidence,
Models, and Explanation
By the end of the 2nd grade, students should know that:
- A model of something is different from the real thing but can be
used to learn something about the real thing.
Common Themes: 11b Models: K-2
- One way to describe something
is to say how it is like something else.
Common Themes: 11b Models: K-2
By the end of the 8th grade, students should know that:
- Energy cannot be created or destroyed, but only changed from one
form into another.
The Physical Setting: 4e Energy Transformation: 6-8
- Models
are often used to think about processes that happen too slowly, too
quickly, or on too small a scale to observe directly, or that are
too vast to be changed deliberately, or that are potentially dangerous.
Common Themes: 11b Models: 6-8
- Different models can be used
to represent the same thing. What kind of a model to use and how
complex it should be depends on its purpose. The usefulness of a
model may be limited if it is too simple or if it is needlessly complicated.
Choosing a useful model is one of the instances in which intuition
and creativity come into play in science, mathematics, and engi-neering.
Common Themes: 11b Models: 6-8