SP4 Students will investigate the properties of waves.

SP4 Students will investigate the propertiesof waves.

Warm-up:

1. An electromagnetic wave begins with an electricCharge (like an electron).

2. The electric charge has an electric field

3. The electric field creates a magnetic field

4. These fields are perpendicular to each other

5. This transverse wave has a wave length.

Austin Lanham’s Quantum Physics’ DoubleSlit Experiment

Photons depend on the frequency of the wavenot the amplitude (energy).

Objects can absorb light, reflect light, and transmit light depending on the typeof matter they are made of.

Opaque only absorbs light and reflects it.The blue cup is an example of an opaque material.

Aluminum foil is an example of an opaquematerial because it reflects light

Translucent materials allow some light to passthrough them. Which cup is translucent?

Transparent materials transmit almost all the light.The clear plastic cup is transparent.

Wave Properties of LightReflectionRefractionDiffraction Interference

A. Reflection

• Reflection– when a wave strikes

an object and bounces off

incident beam reflected beam

Normal

The Law of Reflection says that the angle of Incidence always equals the angle of reflection.

Diffused reflection

B. Refraction

• Refraction– bending of waves when passing from

one medium to another– caused by a change in speed

• slower (more dense) light bends toward the normal

SLOWER

FASTER

• faster (less dense) light bends away from the normal

B. Refraction

• Example:

View explanation.

C. Diffraction

• Diffraction– bending of waves around

a barrier

D. Interference

• Interference– constructive brighter light– destructive dimmer light

Every material has an index of refraction, the larger the index, the greater the amount by which the speed of light is reduced.

Car side mirrors do not work when theyare covered in frost. What does frostdo to the surface of a mirror to causediffuse reflection?

There are twoareas in thispicture thatshow lightrefraction.What is causingthe refractionin both?

Each wave length of visibleLight is a different color.When an object reflects that wavelength weSee that particular color.

B. Seeing Colors

• White light– contains all visible colors - ROY G. BIV

• In white light, an object…– reflects the color you see– absorbs all other colors

REFLECTSALL COLORS

ABSORBSALL COLORS

B. Seeing Colors

• The retina contains…– Rods - dim light, black & white– Cones - color

• red - absorb red & yellow• green - absorb yellow & green• blue - absorb blue & violet

Stimulates red & green cones

Stimulates all cones

B. Seeing Colors

• Color Blindness– one or more sets of cones

does not function properly

Test for red-green color blindness.

C. Mixing Colors

• Primary light colors– red, green, blue– additive colors– combine to form white light

View Java Applet on primary light colors.

EX: computer RGBs

C. Mixing Colors

• Filter– transparent material

that absorbs all light colors except the filter color

View Java Applet on filters.

C. Mixing Colors

Light Pigment

When mixing pigments, the color of the mixture is the color of light that both pigments reflect.

Bright colors are constructive interferenceDim colors or black fringes are destructive interference

C. Mixing Colors

• Pigment– colored material that absorbs

and reflects different colors

• Primary pigment colors– cyan, magenta, yellow– subtractive colors– combine to form black

EX: color ink cartridges

A filter is a translucent material that lets oneor more colors pass through, but absorbsthe rest. The color of a filter is the colorof light that it lets through.

If you looked at green grass with redSun glasses, the grass would look black.

The color green reflected to your eyesWould be absorbed by the glasses.Since the glasses only let red light through.

Choices

• A – Home interior presentation

• B – Teaching a class of Bass Pro Shop on the art of spear fishing

• C – Teaching a 4th grade class on mirrors

Groups: Choice A Soft Blue Book page 212Using the materials provided you, preparea home interiors presentation on the following:

The types of windows available for an upstairsbathroom. Based on the science of light, and thecustomers’ needs, explain which window worksbest under certain conditions.

Choice B

You are making a presentation and teaching a class for Bass Pro Shop on the art of spear fishing.

Be sure to discuss the behavior of light in different mediums and the index ofrefraction using the materials provided you.

Choice C

You are teaching a 4th grade class on mirrors.Design a hands on activity using the materialsprovided for your students to learn aboutthe laws of regular and diffused reflection.You might want to use a County Fair themeand make a fun house with different kinds of mirrors.

Please read the paragraph on page 215.What causes the mirage below?