# SP4 Students will investigate the properties of waves.

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SP4 Students will investigate the properties of waves.

Warm-up: 1.An electromagnetic wave begins with an electric Charge (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 Austin Lanham’s Quantum Physics’ Double Slit Experiment

Photons depend on the frequency of the wave not the amplitude (energy).

Objects can absorb light, reflect light, and transmit light depending on the type of 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 opaque material because it reflects light

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

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

Wave Properties of Light  Reflection  Refraction  Diffraction  Interference

A. Reflection Reflection – when a wave strikes an object and bounces off incident beamreflected 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.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 they are covered in frost. What does frost do to the surface of a mirror to cause diffuse reflection?

There are two areas in this picture that show light refraction. What is causing the refraction in both?

Each wave length of visible Light is a different color. When an object reflects that wavelength we See 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 REFLECTS ALL COLORS ABSORBS ALL 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.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.Java Applet on filters

C. Mixing Colors LightPigment When mixing pigments, the color of the mixture is the color of light that both pigments reflect.

Bright colors are constructive interference Dim 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 one or more colors pass through, but absorbs the rest. The color of a filter is the color of light that it lets through.

If you looked at green grass with red Sun glasses, the grass would look black. The color green reflected to your eyes Would 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 4 th grade class on mirrors

Groups: Choice A Soft Blue Book page 212 Using the materials provided you, prepare a home interiors presentation on the following: The types of windows available for an upstairs bathroom. Based on the science of light, and the customers’ needs, explain which window works best 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 of refraction using the materials provided you.

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

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