# Physical Science B SGI Lesson #15 (3-11-2019)

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.

### Course Digital Resources:

IMPORTANT REMINDERS:

Event #1 (THIS WEDNESDAY)

3-13-2019: Students must be at school by 8:30 AM for the Cabrillo Trip! Bus leaves at 9 sharp and we will be back at 2pm at the latest.

Event #2 (Next Wednesday)

3-20-2019: Engineering Design Challenge at 9AM.

For those of you who did Physical Science A with me in Fall 2018, remember the lunar drop we did with the egg? Well, this design challenge will be very similar. Both Biology and Physical Science Students will be working together in the large classroom here at the Wilson Center starting at 9AM on this challenge.

### 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.

### Background:

The Philadelphia Experiment is an alleged military experiment supposed to have been carried out by the U.S. Navy at the Philadelphia Naval Shipyard in PhiladelphiaPennsylvania, sometime around October 28, 1943. The U.S. Navy destroyer escortUSS Eldridge (DE-173) was claimed to have been rendered invisible (or “cloaked“) to enemy devices.

The story first appeared in 1955, in letters of unknown origin sent to a writer and astronomer, Morris K. Jessup. It is widely understood to be a hoax; the U.S. Navy maintains that no such experiment was ever conducted, that the details of the story contradict well-established facts about USS Eldridge, and that the alleged claims do not conform to known physical laws.

The experiment was allegedly based on an aspect of some unified field theory, a term coined by Albert Einstein to describe a class of potential theories; such theories would aim to describe — mathematically and physically — the interrelated nature of the forces of electromagnetism and gravity, in other words, uniting their respective fields into a single field.

According to some accounts, unspecified “researchers” thought that some version of this field would enable using large electrical generators to bend light around an object via refraction, so that the object became completely invisible. The Navy regarded this of military value and it sponsored the experiment.

### Assignment:

Step #1

Go to Google and create a Google Doc entitled – “Unit 8 Waves Paper – Philadelphia Experiment”. Share it to me at ChristopherTyler@emsofl.com

If you don’t remember how to create a Google Doc click HERE to be taken to a How To Guide.

Step #2

After you have created and shared your paper. You will begin writing a 5 paragraph paper addressing the question “Can waves be manipulated to the point they could purposefully hide a massive object?” Below is my recommended outline for your paper. You can can set up your paper however you like, the outline below is just a recommendation.

Paragraph 1 –

Paragraph 2 –

Introduce your reader to transverse waves. What are they? Where can they be seen? Do they use a medium?

Paragraph 3 –

Introduce your reader to electromagnetic waves.What are they? Where can they be seen? Do they use a medium?

Paragraph 4 –

Given what you know, is it possible for waves to hide a massive object purposefully? Why or why not? Explain your answer.

Paragraph 5 –

Why should the reader care about this topic? Why should the average person know what waves are, how they work, and their potential?

Assignment Resources:

YouTube Video -> Experiment a Hoax

Upon completion of the Philadelphia Experiment project, make sure to go over this check list so you can close your Unit 8.

Unit 8 Items:

• Philadelphia Experiment Analysis Paper – Printed and handed to Mr. Tyler (New as of today)
• Powerpoint Presentation on Waves – Printed and handed to Mr. Tyler(Previously done)
• Vocabulary Test – Passed with above a 70% – Mr. Tyler will confirm and print (Previously done)
• Have Mr. Tyler confirm your handout work is in and complete – Remember Mr. Tyler collects most of your work before you leave. (Previously done)
• Unit 8 Test – Passed with above a 70% (Last thing before closing unit)