INTRODUCTION

Purpose: investigate properties of sound and light waves including amplitude, frequency, wavelength, and wave speed

Read over the entire lab procedure below, then complete each task and record your findings in the data section at the end of the lab. 

Upon completion, save this document as a PDF with your name in the filename in the form “Yournamehere-waves.pdf” and upload to the assignment box on online campus.

Background: Waves encompass many different physical phenomena. Physical waves include tidal waves and standing waves on guitar strings. Light is a special type of electromagnetic wave. Sound is a pressure wave. Although the waves differ in their type and properties, they share a common basic structure. 

We can represent waves in terms of oscillations with amplitudes, frequency and wavelength. 

                   

The speed of a wave is related to its frequency and wavelength. The frequency, f, is how many oscillations of the wave occur per second. The wavelength,   is the distance between two similar amplitude points of the wave. The amplitude of the wave is the height of the wave (and is related to the intensity of the sound or light wave).

PROCEDURE

A. Part 1: Test your hearing!

1. For sound waves, the frequency of the wave is more commonly referred to as pitch. 

2. Go to Tone generator Application (http://www.szynalski.com/tone-generator)

3. First: Explore. Pick several music notes and test the difference in sound.

4. Next, test your hearing range: Healthy young adults should be able to hear sounds in the range of 20Hz to 20kHz. What range of frequencies can you hear? Test other people in your home, especially older people.

5. Finally, open two tabs and explore what happens when you set them to play two different frequencies. What happens when the frequencies are close to each other?

6. Based on your investigations answer the attached data sheet questions.

B. Part 2: Interference

1. Open the PhET simulation Wave Interference.  (https://phet.colorado.edu/sims/html/wave-interference/latest/wave-interference_en.html)

2. First: Explore the simulation to get a feel for the controls.

3. Next, test your hearing range: Healthy young adults should be able to hear sounds in the range of 20Hz to 20kHz. What range of frequencies can you hear?

4. Using the simulation options (try each of the different waves, interference and slits settings), compare the four scenarios. What do you think might be happening to the light to create these different patterns? Write your ideas in the space on the answer sheet.

 

LAB 5 – Waves Data Sheet

   

Name:

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Date:

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A. Part I: Test your hearing!

1. What happens to the sound as you increase the frequency?

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2. Record your hearing range. Can you hear the full healthy range, 20Hz to 20kHz? What about others you testing? Did you notice any hearing loss with older people?

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3. Describe what you hear when you play two different frequencies (that are close in frequency but not exact). What’s going on?

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B. Part II: Wave interference simulation

1. Try to recreate the pictures shown in part B with the simulation. Describe what you had to do with the simulation to reproduce the pictures.

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2. Compare what you learned from the simulation to your ideas from page 1. What ideas would you keep? What ideas would you change? (Did you notice the third bright spot right behind the wall in case 4?)

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3. What happens to the pattern on the screen when the lights are brought closer to each other or farther apart?

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4. What happens to the pattern when the slits are brought closer and farther apart?

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