# Hands-On-Physics WAVES

## - Overview -

Background
Our eyes don't reveal everything, and we have no organ that can signal with light. Much can be revealed and much can be communicated by other (non-visual) means. Sound is a meduim for sending and receiving messages of many kinds. It is especially important to humans because we constantly listen in the sea of noise around us for significant sounds. We also make sounds in wonderful and complicated ways to communicate and to just plain have fun.

Sound is a good phenomenon to study because it is so familiar and because the formalism, which has been developed for describing sound, works equally well for other kinds of waves. The mathematical model for waves is central to the study of sound. The wave model also has applications in mechanics, electronics, optics, and quantum physics. Understanding the wave model is an essential part of understanding physics.

Goals
Understanding and controlling sound requires knowing some important physics that is central to this unit. You start by getting a sense for pitch and tamber and then go on generate sound electronically. As the unit unfolds, you are introduced to the major concepts of wave motion, that are usually taught in physics, through a series of interesting projects.

By the end of this unit, you should be able to:
• Order pitches (from low to high).
• Measure pitch (frequency) using an oscilloscope.
• Use the various units commonly used for frequency,wavelength, and speed.
• Construct, describe, and evaluate, an electronic tone synthesizer.
• Compare the relationship between the physiological perceptions of pitch, tamber, and loudness with the ideas of frequency, wavelength, amplitude,and wave form.
• Give operational definitions of wavelength, frequency, and wave speed
• Build electronic equipment for studying sound.
• Measure variations of sound intensity.

### The Learning Strategies:

Learn by Doing
Most people learn concepts by making things and then thinking about them. Too often students try to jump ahead and memorize the equations and definitions without giving themselves time to think. This is why Hands-On-Physics units emphasize "hands-on" building.

HOP Structure
There are three major sections to each unit: "messing around," a "core project," and then "extensions." The "messing around" part is a chance to learn the big physics concepts without worrying about a lot of details and computations. The "core project" is an extended construction project that everyone does. Then you choose one of a number of "extensions" to work on.

Think in Lab
It is important that you use your mind while you are in the lab doing these various projects. You cannot just follow the directions and fill in the blanks. We don't tell you every little step because you should be learning how to do things yourself. Eventually, we want you to be able to undertake an entire project. To get to this level, you have to make larger and larger steps without help.

Fill in the Gaps
You may find this frustrating. You may get mad at the instructions that seem vague and you may wish your teacher could help you all the time. But before asking for help, talk it out in your group; try to invent a way out of your problem. If you are not sure whether you are doing the "right thing", write down what your problem was and what you decided.

Make Mistakes Rapidly
Remember, it is okay to make mistakes; we learn from our mistakes. Always think about safety and try to avoid breaking things. But if you make a mistake, don't be discouraged; just try again. The more mistakes you make, the more you must be learning.

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