# Physical Science B SGI Lesson #14 (2-25-2019)

Waves

8

### Objectives:

• Explain that waves transfer energy, not matter.
• Distinguish between mechanical and electromagnetic waves.
• Summarize the major properties and behavior of waves, including (but not limited to) wavelength, frequency, amplitude, speed, refraction, reflection and diffraction.

### Vocabulary/Definitions

amplitude: How far the medium (crests and troughs, or compressions and rarefactions) moves from rest position (the place the medium is when not moving).

compression: When the particles of a longitudinal wave are close together.

compressional (longitudinal) wave: A wave in which the medium moves back and forth in the same direction as the wave.

crest: The highest point on a transverse wave.

diffraction: The bending of waves around an object.

electromagnetic wave: A wave that does not require a medium to travel, for example, it can travel through a vacuum. Also called an EM wave.

energy: The capacity to do work.

frequency: How many waves go past a point in one second. Measured in hertz (Hz).

mechanical wave: A wave that requires a medium to travel.

rarefaction : When the particles of a longitudinal wave are far apart.

reflection: When a wave bounces off a surface.

refraction: When a wave bends.

transverse wave: A wave in which the medium moves at right angles to the direction of the wave.

trough: The lowest point on a transverse wave.

wave: A disturbance that carries energy from one place to another.

wavelength: Distance between one point on a wave and the exact same place on the next wave.

additive color system: Involves light emitted directly from a source, before an object reflects the light. Mixes various amounts of red, green and blue light to produce other colors. Examples include computer monitors and TVs.

concave or negative lens: A lens that diverges or spreads out light rays.

convex or positive lens: A lens that converges or focuses light, and can form images.

cyan: A highly saturated green-blue that is the complementary color of red and forms, with magenta and yellow, a set of primary colors.

laser: Acronym for light amplification by stimulated emission of radiation. Lasers only produce one wavelength of light, resulting in a beam of light that is very distinct and does not spread out.

opaque: A characteristic of an object that does not allow light to pass through; it absorbs or reflects all light.

prism : A transparent optical object that refracts light.

subtractive color system: Creates color by subtracting or absorbing certain wavelengths of color while reflecting other wavelengths back to the viewer. Examples include photographs and printed magazines.

translucent: A characteristic of an object that can be seen through, but not clearly; it absorbs, reflects and transmits light, such as wax paper or frosted glass.

transparent: A characteristic of an object that allows almost all the light to pass through, so it can be seen through clearly, such as glass or clear plastic.

electromagnetic radiation: A phenomenon that takes the form of self-propagating waves in a vacuum or matter. It is comprised of electric and magnetic field components that oscillate in phase perpendicular to each other and the direction of energy propagation. All travel the speed of light.

electromagnetic spectrum: The range of all possible frequencies of electromagnetic radiation.

### Engineering Connection

Engineers apply their knowledge of waves to design an array of useful products and tools, many of which are evident in our everyday lives. For example: microwave ovens, x-ray machines, eyeglasses, tsunami prediction, radios and speakers. Engineers must understand all the properties of waves and how waves can differ from one another in order to design safe and effective products. To predict how tsunamis will travel after a ocean earthquake, engineers must understand wave properties and how they travel. Engineers also use their understanding of wave properties when designing electronics—to separate different types of waves so that radios tune in to the right stations, or so your cell phone only picks up the calls that you want. Before designing a solution to a challenge, engineers conduct research and gather information as a crucial part of the engineering design process. Through this legacy cycle lesson, students begin to gather the knowledge necessary to come up with a solution to the engineering challenge outlined in lesson 1 of this unit.

### Agenda:

Let us see how much studying we have been doing regarding our vocab terms for this unit.

Enter “A89559b4”

Introduction to Waves

Three key knowledge areas:

1. waves and wave properties,
2. light and the electromagnetic spectrum
3. Structure of the eye

Let’s start this task with what we already know. Why are we able to see? (Because there is light.) What is light? (It is a wave.) So, what is a wave? Well, we will learn the answer to that question today!

I will pass out an outline that will help you keep track of the important concepts explained as we talk about waves and wave properties.

YouTube on Waves -> Intro to Physics

### Task #6 (Introduction to Electromagnetic Waves)

Now you are going to create a Google Slideshow for your Vocabulary Terms for this Unit. The slideshow needs to have a Title slide with your name on it and topic.

Each slide needs to have the following:

Term:

Definition:

Example:

Picture/gif for a visual representation.

The best presentation get a \$20 Amazon gift card! Student will anonymously vote on the best slideshow. I will show you how during Wednesday’s class.

Regulations to aware of:

• Slideshow must be complete
• Slideshow must be shared with me (ChristopherTyler@emsofl.com) by 9AM this Wednesday (2-27-2018).

### Resources:

Website with .gifs -> Types of Waves

### State Standards:

Disciplinary Core Ideas

PS4.A: Wave Properties

• Sound can make matter vibrate, and vibrating matter can make sound. (1-PS4-1)

• Objects can be seen if light is available to illuminate them or if they give off their own light. (1-PS4-2)
• Some materials allow light to pass through them, others allow only some light through and others block all the light and create a dark shadow on any surface beyond them, where the light cannot reach. Mirrors can be used to redirect a light beam. (Boundary: The idea that light travels from place to place is developed through experiences with light sources, mirrors, and shadows, but no attempt is made to discuss the speed of light.) (1-PS4-3)

PS4.C: Information Technologies and Instrumentation

• People also use a variety of devices to communicate (send and receive information) over long distances. (1-PS4-4)

### Lesson Sources:

Website – TeachEngineering STEAM – Apples

Website – TeachEngineering STEM Curiculum K-12

Website – Light Properties

Website – NGSS for California Public Schools